I understand your dilemma. We've tried business opportunities as well. He's hoping to help his family out financially and be able to afford some things he might want, but can't justify the expense with a single income...and probably figures that some time away from the family now is a small price to pay for future potential incomes that the business opportunity will hopefully provide.
What we found was that you can "work the business" and spend time with your family if you add a little perspective, plan your time wisely, and use that time effectively. Most business op's require time to make calls and have meetings. He could set up 2 nights to make calls, 2 nights to have meetings, and one night mid-week for either "family night" or to give you a "mom's night out".
I have a 5 year old and a 2 year old. We both work, so our time with our kids after work and before bed is precious. Even though the business opportunity we worked at was "before kids", if we were to "work it" now with kids, 5-8 is "kid time" and after bedtime is "business opportunity time". To make calls, 7-9pm is a good time. Nights he'd schedule meetings, you might be on your own, but it likely wouldn't be every night, at least at first.
He doesn't have to come home at 5, wolf down dinner, then "work the business" until bedtime. If he can prioritize his time and workload, then he can spend time "doing the business" and with the family.
Further, is this business something you can help him with?
(I think if I had been in your shoes, I would have told him, "Okay, you can work the business in the evenings, but I work all week too as a SAHM (which many experts say is equivalent to working 2 full-time jobs). I get Wednesday night off for 'Mommy's night out'.")
For what it's worth, and good luck!!