[rrrrrrrrrrrryan]

A question like "Do you have any allergies?" probably requires ternary logic: yes/no/unset

Discrete events are usually more binary by nature: a thing either happened or it didn't.

That said, if it's possible for an event to un-happen, you're back in ternary-land: there's now a distinction between un-set and false which may be important to capture.

There's a reason why relational databases use ternary logic when most of the rest of the computing world uses binary logic.

You might argue that you could just create a brand new event, but now you've almost assuredly changed the grain of your table and goofed up the primary key. Your nice normalized table is now a dumb, non-performant endless event log: good luck with indexing that table and tuning those SELECT queries.