From the timeline available online, it's not been proven beyond a shadow of a doubt that something untoward happened.
The kindest possible reading has them interacting very sporadically throughout Matthew's adolescence: Schofield being a celebrity patron and the kid reaching out to him whever possible, Schofield kindly helping land him a gig on This Morning later on and the relationship becoming adult/romantic once a now grown McGreevy was working full time at ITV and became Schofield's personal assistant, ie when he was over 18 and a willing, consenting adult.
There are other possible readings of the dynamic - far more grim and perhaps even more realistic. It's possible Schofield had McG on his radar for years and that the few stray Twitter interactions documented are just the overflow of a bigger, unseen relationship (carried out via DMs, messaging, Snapchat, whatever), that Schofield helped him get a job on ITV because he fancied him beforehand and wanted to be around him/have power over him, that S. had him become his personal assistant because they were somehow involved (or about to), and generally abused his power and influence to make things happen, only coming out of the closet to avoid a scandal exposé, etc.
I suspect many (GP, internet masses) are condeming him off the bat because of his brother and a general pathologization of/reticence towards male-male relationships. Didn't Prince Philip meet Queen Elizabeth when she was a very young girl? As did Charles with his cousin Amanda and then Diana? And yet no one accuses them of anything untoward (criminally speaking). If Philip S. had come out and said he was dating a younger guy wouldn't
To be clear, I'm not saying he is innocent, or even that that's the most likely possibility. I just think we should be wary of how the internet accelerates (even imposes) fairly superficial snap judgements on complex, multi-tiered situations based on incomplete data sets, with him being tried and sentenced by the online tribunal of public opinion. without any actual hard documented evidence or the most important aspect of all, a manifestation from the would-be victim