False. Empoyees of a 2 billion dollar corporation deciding to demand free labour from the community to accommodate what they've decided by fiat is the new Right Way is incredibly insulting. The tmux developers do not exist to serve your whims. The community is not here to save you money.
Isn't the usual answer to this, "If you don't like it, fork it?"
If you work on a large FOSS project, you will spend a lot of your time reacting to decisions made by other people. You won't agree with all of them. Some of those decisions will be made by $2B companies, some of them will be made by influential individuals like Linus and Lennart. Still others were made 20 years ago by some anonymous person in their basement.
Either way, if your complaints fall on deaf ears, your options are limited to living with it or forking it. That's just how it works.