I don't often eat steak. It's not one of my favorite foods. I have used a pocket knife to cut steak once - Vic Pioneer. It was, in fact, a nice steak restaurant and not inexpensive. But the knives they provided were crap, and my SAK is a razor. It made nice perfect slices. The waiter chuckled at it and I mentioned if they had sharp knives, I wouldn't need it.
When I eat out, it is usually at casual dining establishments. Some would be better described as bars with a very good kitchen. One of my favorites provides plastic utensils in the little sealed plastic packets. No problem when eating a burger, but they serve these wonderful really large onion rings. Those work much better when sliced up, rather than biting into it and having the onion pull out of the breading, leaving you with half an onion hanging out of your mouth and an empty breading in your hand. I have used a pocket knife several times for that purpose, to very good effect. Usually a Case Stockman or Trapper. I suppose I could just ask the waitperson for a sharp knife, but why would I need to do that when I *have* a sharp knife?
So yeah, I see nothing wrong with it. Heck, Shun/KAI even sell two different models of folding, locking "personal steak knives" so it's not like it's unheard of (which
Hackenslash
posted a pic of while I was composing this post).
At home I have a number of good, sharp knives in the kitchen which I use for all food tasks. No need for a pocket knife.