The old version of Onguard won't work on MAC OSX 10.10 due to agent controller service is failed to register. We have fixed those issues on 6.3.6/6.4.1 pacthes. So, technically Onguard works on Yosemite over and above 6.3.6/6.4.1 patches.
The unified agent VIA component still has issues on MAC OSX 10.10 which are going to be fixed on next upcoming 6.4.x patches.