Crooks was registered as a Republican voter but records show he gave $15 to a progressive political action committee on the day Joe Biden was sworn into office.
OK, so the signs were in his family's yard. This means his parents were supporters and the kid grew up w/ conservative parents. My guess (and this is just a guess) is his actions were in part a rebellious act against his parents.
He was a young man still finding his way. Even accepting the fact that he had conservative leanings, that doesn't preclude the possibility of him doing something to lash out at his parents particularly if that something involved causing the death of a prominent "conservative" his parents hold dear. My presumption is that his conservative parents were strict and overbearing, which isn't a stretch based on my own experiences.
We really don't have a lot of facts here. What we have so far:
He ranted against paedophiles.
He was a registered Republican.
There were Trump signs in his (family's) yard.
He was bullied in school.
A donation was made in his name for $15 to an Act Blue subsidiary.
He was denied being on the rifle team due to his behaviour and his lack of skill with a rifle.
And that's about it. Not much room to base your guess.
It's just as likely that he bought into the notion that the elites are all a bunch of baby-eating, baby-fucking Satan worshippers, but NOT the notion that that only applied to the Left, and tried to remove a Right-Winger with a history of visiting powerful men and diddling kids on exclusive islands.
My guess was based on knowing that his parents were likely conservative (owing to the signs in the yard). In my experience conservative parents are often stricter than more liberal leaning parents. If that was the case here then knowing he was bullied and denied being on the rifle team, I can imagine that things weren't exactly chipper for him in the family home either.
My guess was, of course, just speculation. However, I would urge whoever is investigating his actions to look into the family situation to get a better picture of what might have motivated the young man's actions.