So as someone who's been working as a recruiter in the industry for almost 9 years now, I can bet on it and say that he probably was asked by other production companies to perform for them and he may have turned it down. Just because we didn't see him do something more serious like Gayhoopla, Men.com, or Sean Cody, doesn't mean he wasn't approached by them or one of their competitors.
I also think it has to do with Marcel seemed so unsure of himself in the different jerk off videos he did. Usually went straight guys take things to the next level beyond just creating teasing content and prancing around naked for these adult companies, a lot of them aren't so sure they really want to masturbate and have sex on camera, even though it is a lot more money.
But you can always tell the difference between the ones who are confident in what they're about to do compared to a person who looks like he's about to kiss someone for the first time. But the point is, he may not have wanted to take it any further than what we saw from him.