I've seen this happen in both good and bad ways. Bad- when someone is trolling and are kicked from a group, immediately requeuing and getting back in, as happened to your fc mate. When its a tank or healer which are rarer than dps, it's likely they'll get back in the same group.

Good- Ive had friends go into groups, ST for example, that are full fc groups aside from them who kick them out before a specific boss because they dont want the person not in their fc to get loot over someone they're competing with on the same job.

I have no idea how hard or easy it is to implement a fix to not let them back in the same group (though it would be handy). Hopefully someday they do, in the meantime its best to just wait a couple minutes before hitting the find new member, as suggested above. If the kicked person was a tank, they'll likely get an instant or very quick queue anyway for a different group, and they'll get a lockout penalty if they withdraw from that window when they see it's not the in prog one they were just doing.