Yes, they can it eat it. It is high in water content, so limit it to small amounts or they may end up with loose stools. Keep in mind it's not high in food value, but as part of a balanced diet it's fine for them to have a small taste every now and then. Not everything needs to have high food value.
I saw a video of someone feeding their adult leopard a rib of celery. They held one end and like a conveyer belt, fed it into the chompers. It was cute, so I totally wanted to try it one day with a piece of my celery. (I don't think I've ever hand fed Levi and he's almost 3). He wasn't interested.... He wouldn't even try it. Lol. Maybe I should try hand feeding more often.... lol
You already have your answer that yes they can in moderation. Just thought I'd share my attempt at feeding the celery