Why should they not monitor the other chain and instead close down completely? That makes no sense businesswise.
You can't just watch as you are risking the loss of your fiat - so any sensible business is going to put up a sign like this:
"Sorry - no fiat withdrawals until the fork situation has been resolved."
I did this before I read your post.

OK, so I'm only buying Satoshis, and I'm only a small node operator, but there must be many others who are starting to think like this.