If that's the case it means that they can show the "Now boarding - remain seated" only to people that will board in economy seats. I don't think that they can, so it's a bad message that probably came into existence because of some entertaining concatenation of events that somebody in the airport business could be able to explain. But will anybody working in airports read that post?

>If that's the case it means that they can show the "Now boarding - remain seated" only to people that will board in economy seats.

That's physically not possible if all you have is a single display in front of the gate, which is common at most airports. Of course, you can add "First class - now boarding, everyone else - stay seated" but for OP's case where there's reading comprehension issues I doubt that would help.

>I don't think that they can, so it's a bad message that probably came into existence because of some entertaining concatenation of events that somebody in the airport business could be able to explain.

It's not hard to think why it's necessary. Otherwise you have a hoarde of economy people clogging up the gates when it's only supposed to be first class people.