So I feel I can add at least a little credibility to Declan as a person.
I'm from the DC area, where he is/was from. I've ridden with him many many times. He is undoubtedly one of the most skilled riders on the east coast and very knowledgeable about EUCs. I've seen him add heatsinks, make his own battery packs, DiY longboard, crazy scooter/trike inventions, and more. He is basically a mad scientist obsessed with anything that has wheels.
Do I think he is perfect at all of this? No. Does he have a bit of an ego? Not really. He is quite a modest guy and I've never seen him vocally challenge anyone or call them out. He lets his riding speak for itself. Does he help our local community? Yes! He has given me tips when starting out, and when I've had to do repairs or pick out gear. All in all, I believe Declan has good character.
Now, does he know what he is doing with this GodMod stuff? I can def say our DC community is full of memes and inside jokes. I think God Mod got big in part due to that. I have actual friends who have used the god mod and said there was a very small difference, but I think the inside jokes and memes have inflated this to giving a bigger promise than it can deliver. due to injuries and surgery, I have not been able to ride with the group for several months, but I think Declan may just be letting some of this get to his head or get carried away with it. I don't think he has ill intent and I think he firmly believes in his product.
As for him policing the chat and banning people though, that is not cool. He has allowed some pretty gross hateful speech in the DC EUC chat and only stepped in when legit threats of physical violence were coming up often.
TLDR: Declan is a smart, helpful, and humble guy. God Mod has some legitimacy, but is over hyped and the meme has pushed it into something more than it could ever be.