Putin’s helicopter ‘fended off drone attack’

You point out exactly why it would be a good idea for the West to kill Putin. Putin represents an extremely effective moderating force on Russian politics since he became President and especially since he imprisoned Khodorovsky. Putin presided over and enforced a merger of "legal" and "criminal" capital in Russia. It's important to note that in reality these are practically distinctions without difference post-USSR, they could more realistically be called de jure and de facto capital.

If Putin is out of the picture the Russian oligarchy can declare a 90's style free for all on each other once again to figure out who the next guy who can stitch together capitalist power is. In the West these power structures are much more diffuse (but are becoming less and less diffuse) because the governments are "fairer" (read capital class solidarity) kleptocracies and the entire legal systems exist to prevent the nobility from declaring war on each other.

While Putin's replacement may be much more of a hardliner, it's unlikely that they would be more effective at administering the Russian capitalist state and managing it's power constituencies than Putin. There's a reasonable argument to be made that if Putin dies the SMO collapses by way of lack of political will, infighting, and opportunism within the Russian oligarchy. Everyone forgets just how unpopular the SMO was among the elites and the commoners until the state put the consent factories into overdrive.

To get SMO working, Putin broke one of the most durable Russian liberal constituencies, babushka's with dead sons. War is perennially incredibly unpopular in Russia, and it's driven entirely by babushkas who aren't afraid to see Russian jails and aren't afraid to loudly shame every single man involved in their arrest on traditionalist and gender grounds. The actual pro-SMO censor laws for that reason alone work on egregious fines that effectively silence pensioners.

This contingent is also essentially everywhere in the former USSR, but they're often extremely pliable if not through political chicanery through outright consequences for their living situations. It's a political contingent that is difficult to understand in the West because their typical political positions are so heterodox by Western understandings.

Lastly I think after Putin reached critical mass for the SMO in mid-2023, it's been difficult to tell who is actually a true believer in the hardline stuff and who is playing the part. Medvedev doing Zhirnovsky style posting is a bit out of character based on prior history. He literally gave back Gori (large industrial city) and Poti (warm water port) in 2008. They held several key cities past cease fire. So given how he did South Ossetia, I would peg Medvedev would have wrapped things up by now to focus on other things because they have already annexed Crimea + DNR + LNR + Kherson and Luhansk. Compared to Georgia, the Russian state did not need the full court press to sharpen the ideological lines between Russia and Georgia simply because Russians did not care as much. Ukraine is a different story because West of Moscow you will find many people who have family living between Russia, Ukraine and Belarus. Caucuses are culturally different and aren't as intermixed between Russia (there's something like 100k Georgians in RF by the official census mostly in Moscow), so there was no good feelings, cultural similarity and familial bonds to break. More people were arrested / detained for anti-SMO protests than showed up to the largest anti-Georgian war in Russia. I might even be so bold as to claim that the total number of anti-Georgian war protestors in Russia was realistically somewhere below ~2k.

This isn't to say Putin dies and the next day the SMO falls apart. It would be a real test of the RF's stablity if they can successfully prosecute the SMO and align on new leadership without things failing. Either way, it's a bit reflexive to assert that Putin is not a keystone to stability of this whole thing.

Destroyed the entire Russian aviation sector just to lick Obama’s boots by promising to buy Boeing planes from America.

Refused to veto NATO invasion of Libya at the UNSC (Resolution 1973), despite Putin’s plea. The first known public spat between Putin and Medvedev.

I wasn't politically aware when he was president, but he has been very outspoken since the SMO, and very hardline about it. He's the guy drawing the funny maps where Ukraine doesn't exist/is the size of Rhode Island.

Why that helicopter got boobs?

It's not that they have an unwritten agreement, but more of a fact that these kinds of political assassinations open up a whole can of worms. From Russian perspective there's little value in removing Zelensky since he'd just be replaced with another puppet like Zaluzhny who might even end up being more competent.