It's a psychological reaction to having very little control over anything around you to exert more control in any area you can. It's not ironically funny, it's ironically sad.

Perhaps he is a vegetarian. Being homeless doesn't require you to sacrifice your principles.

Did you ever think he might have had a life threatening allergy to certain foods ? It's pretty common.

When asked for money for food a few months back, I offered to buy the guy a burrito. I asked what ingredients he wanted, he suggested no beans to make it easier on his fellow humans...

Did you ever think that I was there and might have taken note of such a thing? There's a difference between "I don't eat meat" and "I don't like corned beef." Do you ever give people the benefit of the doubt, or do you always exploit omissions in order to paint the other in a negative light?