For which bit? For Number 2 I don't think there's much choice - the target member gets Isolated, and no matter whether they're the leader or not, the Fireteam breaks. Why would targeting the Team Leader be less effective?
The only time it matters is for Puppets. For Puppets you need No 2 to kick in (prior to or simultaneously with the Fireteam cancellation) so you can appoint another Troupe Leader so they can continue to be activated after the Troupe is cancelled. As per: https://forum.corvusbelli.com/threads/can-of-worms-g-marionette-puppetbots.24686/page-2#post-144909 Only raising this because it's counter to the position @pyschoticstorm took on the issue in this thread, and he wasn't challenged on that (unsupported) interpretation here.
