Anyone who thinks he is doing it to remove the flight tracker is dumb. It is literally based on open-source data and anyone who can be a threat to Elon can likely access it without following that Twitter account.
This might be a good opportunity to advertise ADS-B data collection: websites like flightradar24, flightaware, adsbexchange are powered by thousands of volunteers that collect and upload ADS-B radio transmissions broadcasted by aircraft. Most of the collection goes through an RTL-SDR dongle, so if you have a raspberry pi or some other machine that's up 24/7 - consider contributing! Minimal radio kit for signal reception (RTL-SDR+simple antenna) costs somewhere around USD50. It's also a good entry point for learning SDR and radio in general.
> Q: I live in XYZ, can you use another feeder there? Where can I see if you need more coverage in my area? Etc.
> A: The answer is simple. If you live on planet earth, yes, ADSBexchange.com could use a feeder at your location. The map may look like you see aircraft in your area, but the truth is you can’t see what you can’t see. To detect aircraft with MLAT, we need a minimum of 4 feeders to receive data and the more receivers see it the better the MLAT accuracy. If an aircraft is low altitude, feeders may have to be within a few miles.
I would also add what each individual site will not say explicitly: with a little bit of Linux configuration skills it's easy to upload to multiple aggregators at once.
But this thread is about location: ADS-B (dependent broadcast) and to a lesser degree MLAT (secondary radar interrogation response), both of which primarily operate on 1090MHz.
With an unmodified RTL-SDR you can receive both, not at the same time and you'll want to swap antennas since the ranges are so different, but still :).
PS. The RTL-SDRs used for ADS-B often feature a modification: an analog filter centered at 1090MHz, which removes all other data but makes the 1090MHz reception better. You shouldn't have the filter if you want to play around on other frequencies with the same device.