OK, I'll humour this argument for a bit. Say an intrepid "spoofer" has accessed a large number of codes to attempt to flood the system. That means he sets up within line of sight of a receiver station. He starts transmitting his spoof. Does he only put strings of data surrounding the geographic location of said receiver or does he push further afield by transmitting bogus data for the entire continent? In the case of TAAATS...I wonder if there is a filter to remove data that is outside the coverage area of said receiver...is he silly enough to attempt this within the coverage of both SSR and primary radar of a major aerodrome?
I have read ONE account that is plausible re-spoofing GPS signals therefore spoofing navigation data and, conversely, ADS-B data. However, this was within the confines of a football stadium and with the means of drowning out, parroting and then streaming erroneous GNSS signals** within a limited field of view of the horizon. Theatre wide?, Id say Buckley's on repeating that experiment in the real world...and that is the closest I have ever seen anyone actually getting close...not even in the ballpark, if you pardon the pun.
**The vulnerability? The receiver carries an updated almanac of the GNSS constellation. The receiver cannot tell if all the satellites do a sudden left turn. It just measures the time delay of the signal and computes a position.