Yes it's true. If you move an aircraft, or a big truck like "fire and rescue" ones, crossing in front of an array of LOC antennas, the LOC "far field monitor" will be in "red condition " during some seconds, because all signal structure will be "moved". Same happens, of course, in front of GP antennas. I've seen it just one hour before more or less, believe me!.
On the contrary, I don't know what will happen in the modern on-board computers that manages the automatic flight, when receiving this distorted signal.
My experience about this systems it's now history, I mean, the autopilot systems in DC-9 and B-727 ( Oh My God, how old am I!
). In that cases, for example, I saw how the autopilot was "rejected" when trying to manage a distorsion in a GP beam on board a DC-9... just over MM.
But today, with this IRS "coverage" that "lederhosen" told us here, and even GPS and D-GPS in the very next future, I hope that safety will be increased in all conditions.
Nice flights!
