That's not what legitimate interest is supposed to mean though.

Legitimate interest is about collection of data necessary to operate your service.

Listening to detect if someone in a user's surrounding is showing a match without license has nothing to do with the function of the application. There's no legitimate interest there.

It is perverted. Legitimate Interest includes hovering up all your data and shuffle it of to 100+ data brokers who 'legitimately' are interested in that data.