I suspect are really 3 questions: Are the labs sincere? Are they right about the danger? Is the regulation they want good policy?
I am not qualified to answer questions 2 and 3, but on questions 1...We have essays and quotes up from Sam in 2015 and Dario in 2017 show these concerns predate any commercial product. Some of my friends who first worked at OAI and then went on to start anthropic would call me to discuss these concerns before anthropic even existed - and I'll add these people are frankly not particularly business savvy, the conversations I had were primarily around what side of history do you want to be on, how will the books write about you? I always said if you don't do this with care and collaboration with governments and society generally, your psyche will pay the price and so will those of your children and grandchildren, that was well received. 4-ish years ago one of them called me to ask for intros to folks who work in academia connected to government policy, I made the intros they had the calls, some months later that person came back to me visibly shaken with how difficult it was going to be to get people up to speed on the potential outcomes, how little had been considered.
My biggest concern these days is so many intelligent/powerful people believe the labs are full of shit, yet they may very well not be.