The issue with that is Voltron and Dreamworks just went through the same thing and they arent hurt despite people acting like they can take down Dreamworks.
And one of the VAs was on and off being the darling of the Klance crowd and that STILL came to nothing.
Same goes for RT.
Barb admitting she likes BB is nowhere as damaging as you make it out to be not even close.
Sure there is some damage but that damage is already being done and most people have already realized its people being stupid.
A good example is the Anti-Jaune crowd who have been calling all sorts of things at RT and Miles specifically for YEARS. And their actions are worth nothing.
Same will go for the BB crowd yes they will throw a fit but it wont really hurt RT at all and people will quickly wise up that its people being Salty over their ship not being true.
Its really not the first time this has happened not even close.
So no I dont think its as damaging as you think as the anime industry has been facing this for almost 20 years now. Back in 1996 or so the writer of Eva was getting Death threats and other stuff for how he was writing the show. Now that one did have an effect because the guy had depression but the anime industry as a whole has wised up.
So no I seriously dont think BB fans getting riled up will be as big an issue as you think. Especially because not all the fans will react like that. Sure you will get the die hard how DARE they not make BB canon crowd but they will be the minority and the rest will be just like okay cool I can still write fanfictions and so on anyways you know like the rest of the anime community does.