I have to say that this seems to work. The program runs, and the notification pops up to inform when the process tries to run. It seems to be doing everything it claims.
Not an actual solution of course but considering the lack of support from Microsoft this is the best we can do.
I have to say this no longer works. After Windoze latest major Update, CompatTelrunner.exe runs as if processblocker weren't even there. :(
Appears to be working again. CompatTelrunner had been moved to the windows.old drectory tree, with the latest Windows upgrade; hence, processblocker got confuzzled about its path, apparently. Set it again, and now things get blocked again.