I find it very weird that their heat pump leaked and the efficiency is only at 150%.
It's not clear at all if this is an crazy outlier or reality.
IF this is not just an outlier than the next proper step from him would be to get the ball rolling with the right people to investigate the status quiet and fixing it.
Fixing is called physics... I am not sure magic words on a page (regulation) will "fix" physics....
if I look at the high end an Amana System[2] and 2 Ton unit (which is more common size in the US) COP drops to 1.7 @ -5 and drops to about 2 at single digits.
[1] https://www.amana-hac.com/pdfviewer.aspx?pdfurl=docs/default...
[2]https://www.amana-hac.com/pdfviewer.aspx?pdfurl=docs/default...
Much of the other information is probably available elsewhere on his site: https://willbrownsberger.com/heat-pumps/
As I mention in another comment, I think the base of the problem is that the heat pumps he has installed are simply inappropriate for his climate.
The question is whether there is such a thing as a heat pump that's appropriate for use in the Northeastern US. It seems unlikely to me that someone with this person's level of engagement would have stupidly chosen to install the wrong kind of heat pump or chosen an installer incapable of recommending the best options.
I live in New York State and the government is nearing the point of banning gas installations in new construction here. I have yet to see any real cost benefit analysis for such a policy in a state with such cold winters.
I disagree that he's unlikely to have chosen a bad installer. They seem to have installed a non-cold-climate heat pump in Massachusetts. If that's true, I think it's strong evidence that they were not competent and should not have been trusted. I guess one could argue that this was a low probability choice, but I think it's as likely there were simply no more competent installers available in his area.