Even with the points in your above post, I think it's tough to make the case that you're posting something unbiased and should have still disclosed that information. Even if you're paid hourly and posting in your personal time, in the end I can't see any situation where positive press for the company you work for doesn't somehow affect you positively, no matter how small the needle.

Saying you don't have any financial interest in a company while you are employed there is almost an oxymoron, even if your incentives are much more diminished than someone who owns equity.