Yeah, it's a bad look essentially saying you should only put young justices on the SCOTUS in order to control it for longer. However, that is not a dumb thing to say. It's logical if your goal is control, which his obviously is. It's why the lifetime appointments are so bad. It encourages putting young, less qualified justices on the court instead of older, potentially more qualified ones.
No, it doesn't apply, at least not for the same logic. He didn't say that because the older people are less capable. He said it because a younger person will give you control for longer most likely. They're lifetime appointments, so the logical choice for maintaining control is to appoint healthy young people, not the most qualified people.
I follow the logic, but I would also argue if the chances are always higher of a sitting President to win the following term, the GOP would have been better off running anyone who had not already held office and can maintain control for a possible 8 years and not just 4? So he would be saying Republicans should have voted for Nicky Haley in the primaries.
Edit: Nah - I guess that is a bit different, because they could argue idiots already liked him, so he stood a better chance at getting back in and they didn't believe she could I guess