I'm allergic to seafood and I can barely stand to walk by this restaurant. I simply can't stand the smell of seafood - it literally makes me nauseous and I can't imagine sitting in that restaurant for hours. If he's particularly sensitive, it could be a disaster from the amount of seafood that will put particulates into the air, especially if it's still a buffet. Cross-contamination would be a definite issue.
Depending on how sensitive his allergy is, just touching things that others have who are eating seafood can be enough to cause a problem. So not just tongs but any surface including chairs or salt/pepper shakers on the table. On the very rare times that I cook seafood for DH at home (and I only will cook breaded seafood to reduce potential particulates and the smell), I have to use separate utensils and if I accidentally touch it with bare hands, I immediately wash my hands. It's not life-threatening for me (or at least hasn't been) but even a small exposure can be hours - sometimes days - of a great deal of unpleasantness.
Again, it would depend of his sensitivity.
My step son can not be in the general area where lobster, shrimp, or crab are cooked…
He Loves salmon, muscles, scollops….
However, he can be around others eating shrimp….
So again the OP is asking I assume, because she wants to be inclusive, to completely exclude this person with out know all the facts of the situation seems …… well you know…
Again I refer to the OP’s question.
“is there anything that he would be able to eat?”
Yes, depending on his sensitivity.
Or will they be able to serve him anything that won't be contaminated by the seafood oil or such?
Again, Yes! Depending on his sensitivity.
The allergy chef will cook a separate off menu meal if needed, in an allergy safe kitchen.
Now, if the boyfriend is like my stepson and would have a reaction walking down the hall….
The even the Yatchman’s has seafood on the menu, but I’m sure the allergy chef again, could cook a meal for him….