Can't take this seriously as long they still keep offering commercial AI services while improving the existing models they already have. (I'm not in favor of just stopping AI development and even if people claimed to stop, they probably wouldn't.) It's like people carrying torches warning about the risks of fire.
I agree with you that some of these people (probably Sam Altman) are likely proposing this regulation out of self interest rather than genuine concern. But I don't think the stance is necessarily hypocritical. I know nuclear engineers who advocate for better regulation on nuclear power stations, and especially for better handling of nuclear waste. You can believe that AI is a net positive but also that it needs to be…
Needless to say, this does not hold for AI researchers.