Don't get it...
They've built an SDR TCAS, which is not really interesting. To get it to do anything, they have to get it *close* to an approaching aircraft - it's physically impossible to pretend to be close, without the next-gen faster-than-light SDR2. And, if they have managed to get their kit near an approaching aircraft, then the target aircraft should get out of the way anyway. There may be some limited mileage in putting it on the ground, spoofing their altitude, and hoping that they can persuade passing aircraft to gently ascend or descend.
Note that 'security' doesn't mean authentication here. ACAS uses 64-bit messages. The Wikipedia article makes the point that it can't be extended to even 128 bits because it would then be too slow to handle high-traffic scenarios.
The only interesting thing here seems to be the comparison of Python and C++.