APG 77 is a very very powerful and capable radar. The 1.7 million lines of code for F-22, majority of them deals with that radar. As for the part that is relevant to this discussion, AGP-77 does frequency hopping, which means the radar changes its frequency based on a random number generator. Even the AGP 77 is in scan mode, a passive radar cannot see it because the later cannot tell if it receive signal or noise. As for EW (Electronic Warefare) capability, F-22 is build according to EWCC (Electronic Warfare Commom Capability), and many other F-22 capabilities are classified.
The bottom line is, many people like that Panzerfaust guy have no clue what so ever, and they don't learn anyway.