Yes, everyone should upgrade. An exploit would use the tmux integration control sequence without your consent.
I finally got around to installing iTerm2 this year. It's great, thanks to you (and to all contributors) for all your hard work! I will say, though, that while features like shell integration sound powerful, I personally choose to keep them disabled in order to minimize attack surface. It would be nice to be able to disable tmux integration as well for the same reason, given I don't use tmux.
EDIT: clarification