Hi Tiaeki
I am still always shocked when I see the depths of incivility that some will descend to.
Normally I would advocate talking with the owner in question, but this sounds like it has gone well beyond that point. There are three avenues available to you:
1) You could issue a notice to comply (it comes under the area of not interfering with ‘peaceful enjoyment’ under the model bylaws) against those tenants making the threats, however the level of violence and agression would make me go straight for the second option as well;
2) Get the police involved with the tenants – their behaviour is intolerable and illegal;
3) Try and obtain proof about the malicious owner – then threaten civil action against this libelious and slanderous behaviour
Hopefully that approach will help….of course you have to weigh up the alternative of taking action which can potentially inflame the situation vs doing nothing, but above all, good luck.