The way I read the PIV entry, it's absolutely fine. (Possibly even preferable - though the entry says "transitive or with en", all the active voice examples use en.)

PIV says that the verb can also take an event as a direct object, without a preposition... but most of the citations include "en" so I think that's probably the more common construction.

I don't think so, because el means out of (a group or series, things like that). So this is talking about out of a group

It can also mean "among". That's how it's used here.