Personally, I don't think so when Leo contacted JJ to meet he thought that Leo wanted to get back together because he wanted the same thing and saw how Leo was affected by the break up, and we saw that he was shock and kinda hurt when it was revealed that Leo wants to be fubu with him (cuz ya know it proves the his theory that Leo only sees him as a personal sex toy), and when Leo pulled the BS of sleeping with multiple people yada yada ya, it infuriated him thinking that their break up was just nothing to Leo, which lead him to anger, jealous, and betrayal(?) and was led to stupid stupid decision on agreeing on the fubu thing and forcing (don't know if that's the right word) himself to Leo who is not prepared/ready for the for the said agreement. He did care about whole "wanting for Leo to do better in racing" thing but this agreement was for him to satisfy some sort of "revenge" he have, he just want to get back at Leo, he wants Leo to feel what he felt, that he was just good for the bed, as we can see I'm chapter 15 he was treating Leo LIKE a prostitute (strong word but accurate, and emphasize on the *like*) by saying the two hours thing, sure people in that relationship don't get cuddlely or whatever but they don't treat each other as just a bed warmer even Leo know the basic my inviting JJ for a drink before the thing. And for Pete's sake they're exes that was not supposed to happened, but is far more common than you think (for people that broke up(outside this story)) and oddly enough they have a good and respectful relationship (well most of the time I heard people who treat there partners as spare meat or whatever, WHICH IS BAD, and I don't want to think of JJ as such thing), and don't treat each other as burden, since they both agree on the relationship that they are in, which is opposite to what JJ's doing, acting like he don't even want to do it, which is fine, if he wasn't the one who invited Leo, I get that he may be pissy since Leo's late, but many thing could've happened in that fifteen minutes, I mean the man literally just finished a race, he could've probably shower and prepare himself and drove to the place for god knows how far.
Conclusion: JJ is doing it out of spite, Leo is an idiot, I love them and I hope they suffer more
(Sorry that it's too long I tried to get my message across)
Looking back, I think JJ didn’t say no to Leo because he feels guilty for him losing his focus and having an accident. And he’s willing to be fuck buddies if it can get Leo back in the racing game.