It's not about the content of any single post; the point of astroturfing is to make that indistinguishable. It's about patterns of behavior, some of which are publicly visible and some not. When someone is using HN to advance the interests of a particular corporation, that's not good-faith community membership, and it breaks the organizing principle of this site—intellectual curiosity—egregiously.
Re your accounts, I'm not sure what has felt capricious and arbitrary to you, but from my perspective it's simply a matter of following the site guidelines and using HN in the intended spirit. We discussed that at https://news.ycombinator.com/item?id=22173082 (but also https://news.ycombinator.com/item?id=22359424). If there's some aspect of moderation that still isn't transparent to you (or anyone!) I'm happy to do my best to explain, and even happier to correct any mistakes. But it would be better to send those to hn@ycombinator.com.