No, Lyn, it's not.
People got mad that Anslo of all people got favorable attention from CCP for something cool that he and several other people did. His point about the freighters post-Caldari Prime was entirely valid - why do some people get a "\o/ yaaaaaaaaaaaaaaay" thread for getting recognition while he gets flames and attacks and accusations of collusion and favoritism under some thin guise of "wait what's Slack"?
I am going to repeat myself another time.
Slack is an IRC analogue (just like EVE's chat system!) with server-side logging and in-line image and video support.
Slack has been openly discussed or mentioned in OOC, many times, since it was set up. Some people have asked about what it was, or googled it themselves, as a result. Some of them signed up afterward. Some people have done neither of those things. It is no more difficult than finding out about or signing up for Backstage, or any other internet forum that is not widely advertised.
And claiming Backstage is advertised in comparison is a bit disingenuous, while we're at it - it had a community spotlight 3 years ago done by Eterne, which didn't increase member count much, and is linked in the MOTD for OOC and Red's District. Beyond that, it's people mentioning it when people have things they've posted, and little else. Which is more or less what slack is getting, minus the MOTD mention - and nobody really reads MOTDs anyway, as I'm sure most of us are aware.
As for my personal irritation, I think Makoto summed it up well.
Someone goes out of their way to create high-quality content, CCP acknowledges it, then haters just crawl out of the woodwork and get mad that their stuff didn't get any attention when it was likely neither relevant to the storyline or sufficiently interesting to be worth a mention, or start throwing around insinuations or outright accusations of favoritism or collusion or gatekeeping, instead of being congratulatory for four of our own getting a whole fucking Scope video and a very small event ingame to occur based on that work, and politely - I stress politely rather than the passive-aggressive sniping that occurred - inquiring about the process by which it happened, or where discussion was taking place.
So Anslo's response really should not be surprising. I've already been pretty near to that point for a few months.