your's was more along the lines of "only marry him if he's richer than you"
I don't think that's what I said at all Matilda. I said that the advice that you could protect yourself against financial vulnerability by marrying was generally true but it may well be reversed if you have significant assets (as I assume the OP does). So the argument that you should marry for financial reasons may no longer be a good one, it may actually be a bad one. I specifically said "I'm not suggesting that you shouldn't get married if you want to".
whether it was a man continuing to work or a man who was planning to become a SAHD.
I genuinely don't think it is the case that there would be a different response if making this to a SAHD rather than SAHM. Indeed I would be very shocked if it was: why would there be a difference?
The moral distinction isn't male/female it is financial dependent/financial provider. If you are very wealthy and encourage your partner to become financially dependent on you, especially if it is to care for your children, then I would consider it morally reprehensible to manipulate the legal position try to avoid recognising that person's dependency if the relationship breaks down. If, on the other hand, you are wealthy and use that wealth to allow you to stay at home i.e. you are financially dependent on the wealth not the other party, then it would be wise for you and your children to take steps to ensure that wealth was well protected so that you could continue in that caring role if the relationship ended.
For all those reasons I think the important moral distinction is not on the grounds of gender but financial dependency. It is true that there is a gender discrepancy in the way those roles are distributed in society and I wonder whether your reaction was because you implicitly assumed a man would be a financial provider rather than a carer despite the fact that the discussion was entirely about giving up income to care?