The hesitation was likely because something like a dozen of their own guys were in there (which they refused to identify at trial, so we only know the ID of one that was discovered), and the guy leading the live fire exercises, Fabio Minoggio, was a paid FBI informant (now cop) who was "psyops" trained 20 year veteran of the swiss military.

No real need to address the standoff, when the standoff is yourself vs yourself, and your own guy is by his own admission providing a "supervisory" role of the live fire.