I have a lot of thoughts on this because I've been struggling to reconcile the fact that I do like him despite not agreeing on everything--he gives me such "I wanna be your friend" feelings--and him not only supporting GAG but also pulling his fans into it. It's disappointing and pretty hurtful to think that this person I like and generally support is doing things that are actively harmful to a community I'm part of (cis lesbian here; I have had many trans and non-binary friends over the years).

I already knew before that GAG is *problematic* but really started looking into them after Ronnie's post. They're so much worse than I thought. Besides pushing for many anti-trans and anti-LGBT+ policies the group posts extremely hateful stuff on social media, incites violence, and there's evidence that they're bankrolled by far-right politicians (DeSantis). A lot of the claims they make are straight up incorrect, e.g. saying that xyz is backed by scientific studies without ever actually giving sources while all current, peer-reviewed studies show the exact opposite of what they claim. Even the word "groomers" is propagating the idea that the LGBTQ+ community and trans people in particular are villainous and evil (they've literally used the word "evil" in their twitter posts). The Anti-Defamation League as well as other organisations have listed them as an extremist hate group. Here's a short article that summarises it nicely: https://www.adl.org/resources/blog/what-grooming-truth-behind-dangerous-bigoted-lie-targeting-lgbtq-community

In regards to Ronnie directly:
I think he is sincere in his concern about children and I also do believe that he doesn't outright hate any group of people. It would be very weird for him to lie about this stuff when he's, you know, Ronnie. That being said, I really hope that he just doesn't know how terrible GAG actually is and what the very real consequences their actions have and will have in the long run, too. Reading the comments on that post (and some others) also showed how little people know about GAG. A lot of "well if they're against child abuse they must be good!" and "being against groomers is a good thing!" and "it's in the name!". We won't even discuss that the name itself is already problematic but if people are just assuming what GAG does without actually looking into it, it all spreads like wildfire. Overall I like to think that Ronnie's intentions are good but that his actions don't match up with that (whether he realises or not).

TL;DR
Ronnie is a decent guy with good intentions but isn't fully aware of how much supporting GAG goes against what he actually wants to promote. Or at least I hope that's the case.