So called "attacks" can be viewed as "constructive criticism" through another lens. Yes, tvOS is great- I have an AppleTV on every TV in my home. But even if we agree it is a great device and OS, there's always room for improvement.
Comparing the best to something inferior shouldn't silence constructive criticism. Instead, when anything becomes best, it then competes with itself to get better. It's easy to make fairly substantial wish lists for what would make AppleTV/tvOS better. I see nothing wrong with that at all. Else, if we have to wait until something like Samsung SmartTV os and apps are as good as AppleTV, there's nothing more to do with AppleTV for probably many years to come. Stagnancy is boring.
And the same applies to iPhone, Macs, iPads, etc. Why bother developing new ones if old ones are judged "best" or "good enough"? And yet, Apple does anyway.
When anything is judged best, it should always strive to improve anyway... not rest on its laurels awaiting 'the rest' to catch up.
And if it actually sickens you to see critical opinions of a tech product, you are far too attached to your favorite tech brand... or perhaps would be happier ignoring places where people post such opinions. Unless your livelihood is dependent on positive reviews of AppleTV, you're being sickened by something that is someone else's problems or opportunities. I hope those people- working at Apple Inc.- take such input seriously and opt to make better AppleTVs and better tvOS.
If your brother is happy with his setup, that's his business. You can make recommendations but then it's entirely on him to take 'em or leave 'em. At your home, you are King of your own setup and can enjoy it all your way.