I seriously doubt Amazon's "A9" will even notice A9Home. The products are radically different and Advantage Six don't share a common (or similar) URL to Amazon's "A9". Additionally no one is going to buy an A9Home thinking "that's that Amazon thing - must have it....".
So Paul "relax" I don't think this is likely to be any sort of issue for either party - Ad6 is *obviously* not trying to trade based on a perceived similarity to anything Amazon do.
Any issues A9Home may/might have will have nothing to do with its name I suspect.