Don't get me wrong, I've grabbed my pitchfork at times in the past and some of them have been massive overreactions but I think this is people saying "Oh ffs! Is nothing sacred?"
Audacity is now joining the ranks (yes, the scale is much different) of Google, Microsoft, <Insert Evil Corp Here>. Whether their intentions are evil or not (I don't believe they are in this case) is irrelevant.
For me, it's another nail in the coffin of owning my own stuff and not having to be connected all the time.
For example, why do I want to use an offline application that can potentially send information about me to foreign countries? What possible benefit is there for me in that?
Of course, I'd imagine that telemetry won't break my app if I don't connect to the internet but it's all part of a pattern of software becoming more and more about what the owners of the application can do to monetise me and what they can get away with (whether that's the plan for Audacity or not... they're still playing in the same field and can easily take a stand and say "we will never use telemetry").
Even if it's made to be opt-out, what happens if an update accidentally (or deliberately) switches it on again? Will it be "oops, sorry about that"!