Brumbar is not "a pure AI vehicle" else it would not have 140/120/100 penetration and deflection damage.
Feel free to provide the numerical value of speed of the brumbar and other units that in your opinion it is inline with.
Are you getting Brummbar to deal with vehicles?
Yes or no.
Are you getting Panther to deal with infantry?
It got pretty strong MGs after all and always racks up 10-20 model kills per game.
I do get KV-2 to deal with med tanks as well, because engaging tanks lighter then itself is also its role, previously it was not able to do its job so it got adjusted.
Just because unit can damage something, doesn't mean its meant to engage it.
Brummbar is as much of AT vehicle as panther is AI.
Argue this as much as you like, you aren't changing specialist roles of these two.