I agree that the police could probably have acted more 'flexible' in the first few seconds before removing the journalist from the event. The other somewhat weird fact is that they showed up in 'cilivian' outfits instead of in uniform.

Yet still the *main* problem is the ambassador lying about that person being an active threat.

E.g. what if that information would have been correct? All hell would break lose if the police wouldn't take such a call serious and the supposed 'threat' would be real and people killed, from that perspective they seemed to have reacted quite civilized and calm.

If the events happened as reported, the ambassador should at the very least be summoned and grilled by the Belgian government.