This is how you get Trisolarians knocking on your door!
Out telescopes aren't sensitive enough to detect the power levels of comm signals that aliens would use internally. Even if SETI saw a random powerful signal that happened to hit us, if the signal doesn't continuously repeat it just gets put into the "random transient, didn't repeat, who knows" bucket, and discarded.
The 100 signals they've detected will be looked at again with telescopes, and when they don't see the same signal repeating, they'll all just be discarded. Even if they were in reality actual emissions from aliens that we happened to see, if they're not intentional, repeating, comm beacons, the signals will just get discarded as unverifiable.
If aliens actually made terrawatt scale comm beacons, we would have easily seen them by now.
Is this not the perfect job for AI today? Just sit there and digest signals for 30 years and report back the top 1000? I'm quite sure it could even work on the algorithms as a side-quest.
Literally thousands of witnesses. It's very odd to say "aliens may exist, but those nuclear weapons officers are crazy, aliens would definitely be sending signals from elsewhere, they would not be and are not here."
[1] 50 USC § 3373 https://www.law.cornell.edu/uscode/text/50/3373
No comment.
According to chatgpt, our current earth-based radio telescopes would only be able to detect signals equivalent to radio leakage from earth at a distance of 1 light year.