I don't understand how people that shoot 60p on the RED convert to 24.
They slow it down. Most people shooting on RED are probably in the upper end of the 'professional' chain, and shoot at the cinema standard of 24p for the 'real time' shots, and only overcrank for the slow motion shots.
I'm not saying it's impossible to do what you want, just that is isn't common, that Adobe tools aren't very good at it, and that there's really no benefit at all from doing it. If you want 24p final delivery, shoot it that way. Any time you need to convert something, you just add more work and the possibility of artifacts to the chain.