I haven’t rtft beyond the first few pages
There are two issues for your dh to consider.
One, as you have already identified, is the demands of the role of a sahp. Done well, it is exhausting and consuming. It deserves respect but, as you can see, gets very little. Which leads to the next consideration.
A gap in employment will damage your dh’s credibility in the job market. What you say about entry level employment, not being on a career track etc makes sense. I think you imagine that he’s at point one on a career ladder so if he steps off he can just start again at point one in a year or two. But he will be competing with fresh graduates/ younger people who don’t have a dubious gap to explain. Sahp doesn’t answer the gap questions; it raises more. As is readily apparent on this thread many people think sahp= time waster/ lazy. This will count against him. He won’t be starting from point one; he’ll be starting from the minus numbers. It may not be insurmountable but it will more difficult.
You both may want to consider whether he will rise to that kind of challenge or be buckled under it.
Keeping up some kind of employment may be better for him in the long term. It may be better for him in the short term too as being a sahp can be a drain on mental and emotional well being.
Or it may be too much to juggle, and detrimentally impact on the quality of care that a small child deserves.
It’s a complex issue that you have to consider in light of the needs of all members of the family.
Don’t underestimate your own needs either. Carrying the financial burden for a family is hard and when one partner isn’t earning independently it does funny things to the balance of power in a relationship.
Try to step away from the judgement all attitudes that just about everyone you consult will bring to this issue and consider it carefully and with clear sight.