I do think it is worth pushing back on the argument that just because data is public or broadcast, that makes aggregation of that data automatically OK. (edit: e.g. many Bluetooth devices are set to be discoverable and so broadcast a unique Id that could easily be tracked an aggregated to reveal a LOT of location data)

I do think there are some strong arguments for allowing the aggregation of flight transponder data. I'd like to people making those arguments (such as the value of transparency in fighting corruption) rather than backing dangerous lines of argument because they don't like Musk or rich people in general.

Edit 2: One of the things that makes what ADSBExchange doing seem OK to me is the fact that in addition to selling the aggregated data commercially, ADSBExchange makes the data publicly available for non-commercial use. To me, that really helps tip the scales as it supports the transparency argument