No, it's not reckless to eat at restaurants that serve shellfish. My son has a shellfish allergy and he eats in the mall the time.
It's reckless to rely on Pepcid as protection. Sure, it provide some protection as an H2 antagonist, but it's probably a #3 choice for allergic reactions. Meaning, we've been told we could use it if there's nothing else around.
If you have a food allergy it can become serious at anytime in your life--whether it's accidental cross contamination of a small particle or not. If you know you have food allergy, I'd be going along to a restaurant with more than Pepcid.
I will rephrase my statement: it's not reckless to take Pepcid. It's reckless to depend on it keep you out of trouble should an accidental ingestion occur.