That's a very fair point but we didn't actually notice it until we got to our overnight (it was one leg out, one leg back). The FA was working the aft cabin, we were running late, we did the briefing basically by interphone, and off we went. So there really wasn't any in-person interaction until we got to the destination and it wasn't until we were walking to the van that we really noticed.
Lots of discussion obviously ensued, with the FA claiming it was 'just allergies'. By the time we got to the hotel the return leg had been switched to a repo (no pax). So at that point, it was like, well, we either all call off now and get stuck here in this hotel for God knows how long, or we just operate the repo and go the heck home.
The three of us (2 pilots and the other FA) agreed that flying home was likely the better approach. At that point we'd already been in the van with the sick FA. For the 14 days at home that have followed, I've been quarantining myself.
Good news is that the sick FA is now fine and none of us have felt any symptoms. So we're likely all in the clear.
Can't say our decision was necessarily the best at the time, but fortunately it turned out OK. Of course, I'm sure many crew members have made similar decisions recently and have had the opposite result