I like to use my phone via Steam Link to repost auctions and simple things like that while watching TV, eating, brb bio, etc. Helps cut down the “chores” when I actually have face time with the computer to play freely and with more than 4 buttons available lol.
Does Steam Link fall into the new banned category of “Input Broadcasting Software”?
Typically speaking, the blues here aren’t really able to approve any specific software.
That said, I know in the past that software that streams your game over a network have been recommended against.
Personally, I wouldn’t play remotely from your PC.
What would be the best avenue to get a response?
Seems weird to add controller support and then go this route if it does in fact apply to programs like Steam Link 
There is not one really. Blizzard reps won’t officially approve any software or methods they don’t own and control. Even if something is ok right now, if that software changes, it could become an issue.
It is best simply not to do something if you have concerns.
Steam link does not violate any of the ToS.
The ToS disallows cloud gaming. You are not allowed to pass through a third party computer. Remotely connecting to your own computer is not addressed in the ToS.
Are cloud gaming and remotely connecting to your own computer similar enough that blizzard may have difficulty telling the difference? Perhaps.
Sorry, but I’m not gonna rely on a player interpretation of what allowed and not allowed in the EULA.
OP, If you use it, do so at your own risk.
it isn’t an interpretation. cloud gaming doesn’t have a mysterious definition. steam link is not cloud gaming.
I don’t think the OP should risk account closure based on what a player says. Unless Blizzard steps in and clarifies, I still stand by “Use at your own Risk”
From a previous thread about this topic:
same from technical support.
I know it has been advised against, here and in tickets. I’m not contesting that - “use at your own risk” is fair enough advice. But it still isn’t against the eula.
It’s a rather moot point fighting about this as anything said here about, namely from players, is pointless as Blizzard can turn around and deem the use of Steam Links as against the ToS as it’d be against their cloud gaming as they see it.
But from last August. Technology is forever changing as time goes on, and especially with the recent changes? It really is use at your own risk and don’t come here crying because appeals fail or a suspension is held up.