You're right, though he is showing that in fact it's hard to get a full and balanced diet using just food stamps as an income. So he's contributing to your point, even if he's not going through a full "challenge" of forcing himself to spend no more than X amount in a month on bills/mainteinance/etc. It's hard to properly emulate what it's truly like to live in poverty.

I don't think the challenge is "what's it like to live as the average person who depends on food stamps" but rather "what's it like (even provided all of the other luxuries in my life) to feed myself for $30 a week". The guy is obviously smart enough to know that he can't properly simulate the former challenge, but if anything at least the latter challenge should shed some light on the difficulty of properly feeding yourself under such a budget.

True. Food can be managed by rationing and not indulging in pleasures, the problem exists beyond food. Unexpected illness, getting from one place to another by public transport, not tending to an illness, thinking about passing out on a bar of mars etc. Poverty makes you helpless.