Sorry, I didn't want to open that can of worms again ......
Although Langhans was associated in the 60s with Dieter Kunzelmann, a radical antisemit who planted a bomb in a Jewish resting homen in Berlin (which fortunatelly did not explode), I don't think that it was antisemitism to invite PG to that castle in Kronwinkl, Lower Bavaria. Nor that the Baader Meinhof gang wanted to hijack PG, leave alone any secret service in the world.
The Highfish /Haifisch (Hai is German for shark) wanted to get in contact with the Stones via PG.
As the state of PG is concerned, it was reported that he took a lot of trips beginning with the first tour in the USA in 68. He changed a lot, listen to the music, watch the pictures (robes and cross on the chest).
Maybe Kronwinkl was just the point where he ran off the rails.
Kronwinkl map
https://www.google.com/maps/place/Kr...7!4d12.0420598