At least they aren't removing it like originally planned. A warning from `adb sideload` or `adb install` that can be bypassed with an environment variable is reasonable IMO.
I'd really like to see details before drawing conclusions. If it really is just an extra up-front warning screen or something then yes that's reasonable. If it's something that unfairly disadvantages F-Droid compared to the much less safe Google Play store, then it's unreasonable.
