1. Add an option: Always extract with host.
You know there's always that one guy who leaves after the first round, but the other 3 can handle it find without him. Oppse, you forgot to check, and he was host. Enjoy your host migration (and all the associated bug risks)
Do you check who is host the very first thing in SO, and always make sure he goes through the portal before you do? I do, because so few people say when they're leaving, and I don't want host migration. Of course, that one time you don't see him and just assume he went through, nope, he was hiding in a corner. Enjoy your host migration, and all the associated bug risks.
You know how even if you're waiting in the elevator on the Zariman with the host, and he leaves squad to extract immediately, you get host migrated and get to wait all over again on your own? With, you guessed it, all the associated bug risks. Today I host migrated in the Zariman into a statue version of my warframe with a frozen timer. Had to kill the client.
I never want any of these to happen. When the host extracts, I want to leave too. Every time. Not everyone agrees, so make it an option.
2. Add an option: Decline all host migrations in orbiter.
When the host leaves group in the orbiter, do I want to host migrate? No, of course not, I want to drop out of the group entirely. Before you say, that's technically host migration (and you might be technically right .. the best kind of right .. if you want to be "that guy"), remember that when you leave group in the orbiter as a non-host, it's seamless with no "host migration" message/lag.
When the host leaves group in the orbiter, do I want one or two other people "joining" my group afterwards (having suffered through said host migration) .. no, of course I don't. If I'm a jerk and don't wait for them to drop first, they might get 2 host migrations. I bet they love that. I think that's how it works, anyway. I might be wrong.
Not everyone will agree, so make it an option.