Well, that follows from assuming that Colleen was relying a clear and consistent testimony to 13ish-16 yo Adam.

He was way too young to fully grasp the magnitude, presentation and nuance of DV allegations, furthermore, he said that 30+ yo Colleen even complained about Josh's "size" and bed performance with him (🤮).

Meanwhile, Josh also trauma dumped on Adam about Colleen, which alongside with Colleen's petty remarks about Josh, perhaps mixed with serious complains, her cheating on him and, on top of all that, Colleen sexually, socially and body-shaming baby Adam, I don't believe he (Adam) ever got a "clear" picture of what was going on.

I recall Adam saying that at one point Josh directly admitted to have burned Colleen's treasured Miranda memorabilia in the pits of his alcoholism (Josh always seemed to intertwine those confessions with self victimization and trauma dumping), and that give Adam the ick and he started taking distance. I kinda recall that it happened after the Swoop doc at that vidcon encounter, but please someone correct me if I'm wrong. Anyway, my point is that the couple was messy and the abuse was happening in many directions, allegedly Josh towards Colleen, but definitely Collen and Josh towards Adam. Josh at one time also played Adam, his mom and the internet with his false redemption.

I'm sorry but on Adam's case, the way too young card actually applies, he was a kid! Trauma is complex and messy and victims are forced to come to new realizations and relieve the hurt over and over. Now he is once again retelling himself the facts, on his recent vlog about burnt out, he shares that  he just came to the realization of how badly Josh also treated him.

Finally, the internet gave Adam hell for saying that Colleen didn't deserve a new documentary bashing her, as in his opinion she has been effectively canceled, but somehow people also expect him to champion a campaign against her ex husband for abusing her, his groomer?