Well I havn't written the documentation cited above. In my documentation I don't have such a general restriction.
The special restriction I have in mydocumentation is written beneath the definition of the call back routine with CALLING|PERFORMING:
A prerequisite for the execution of the callback routine is that the calling program still exists in its internal session when the remote function is terminated. It is then executed at the next change of the work process. If the program was terminated or is located on the stack as part of a call sequence, the callback routine is not executed.
I suspect that the SAP Library documentation cited above got that mixed up and generalized a bit too much..Feel free to open a ticket ....