Nah. The real cancer is the quiet plurality of users who just scroll through the post feed and only voting, not even reading comments. The ones who are responsible for the occasional thread that has entirely negative comments but gets upvoted to the stratosphere anyways.
The two apps are identical and built from the same codebase anyway. K-9 is just a branding asset swap.
I’ve seen conflicting info from Thunderbird devs on how long they actually intend to keep both branding packages active. I’ve heard no longer than a year. I’ve heard only as long as it takes to get Thunderbird out of beta. I’ve heard they have some sort of agreement with FDroid that obligates them to keep it listed for some minimum duration of time (???). I’ve most recently heard indefinitely, because their build script is just a toggle now and it costs them nothing. Which one do I believe? I have no idea. I doubt K-9 will be kept around in perpetuity, though.