As an instructor that teaches people about this kind of thing, I have some disagreements, here...
As a range toy, the 556/223 in 7.5 barrel is a blast to shoot, unfortunately, it can't be suppressed enough to make it a safe indoor home defense weapon.
"Suppression" isn't the main problem with a 5.56 in a 7.5" AR barrel, indoors or out. The issues are problematic cycling in that short of a barrel, impairing muzzle blast, and - inside, at least - a high danger of over-penetration despite the shortness of the barrel. There's also the physical size of the platform to contend with; even a short AR gets unwieldy in a hallway... especially if you have to shoot across it instead of down the length.
However, the same gun in 300 black out can be silenced down to a "whisper" and while being too expensive to shoot for a range toy makes the perfect home defense pistol.
Suppression, again, isn't the main issue. Those with enough training to shoot an SMG in close quarters might be able to make use of something like this, but for most people, that's not the case in a home invasion: adrenaline, panic and disorientation make the AR a more difficult platform than most other options, for the aforementioned reasons. Also, you're
still dealing with a high-velocity rifle round: .300 AAC can hit 2,100 FPS, even in short barrels. I've seen numbers as high as 2,300; I don't know about you, but that's way higher than I'm comfortable with, inside. Also, "perfect" is very subjective...but it's usually whatever someone shoots best, has on-hand, and which is most likely to put lead on target with no accidents or difficulties...and for most people, that's either 1) a striker-fired pistol, 2) a revolver, or 3) a shotgun. I prefer the latter; I steer most people to the second.
My next one will be in 300 BO with the Binary trigger for this reason. I like the idea of having a 50rnd drum for home protection, home invasions happen with 3 or more guys invading.
I would consider that to be a cumbersome combination for the purpose, but if you can handle it: go for it. I have an XM177 that'll eat anything you feed it, and I know I wouldn't want to deal with that gun inside; same goes for the .300 AAC, and the 9mm blowback. Of all of them, I'd take the 9mm, but I still don't like a gun that large inside.