No; the disappearance of content on these tags was coincidental in time, and mentioned in the same article only as inflammatory speculation. Tumblr hasn't said anything to indicate that this was part of their "adult content" changes.
I can guess another, more likely purpose for this particular change... (I'll focus on #gay in particular here, but it applies equally well to #lesbian):
Think about how tags are used on Tumblr--it's a lot like Twitter. People tag a post with something to add it to a conversation it wouldn't otherwise be a part of. So, what gets tagged as #gay?
You don't tag a picture of two handsome naked homosexual men with "#gay", usually; that tag is too vague to serve any purpose. Usually the people who post porn have their entire blog dedicated to one type of porn anyway, so tagging #gay on your Gay Porn Blog would be fairly useless. Even if you did, the Safe Search mode would hit this tagstream just like any other one, so there'd be no reason to censor it in particular if that's all it was.
So, #gay != gay porn, okay. So, maybe #gay is/was for rights/social justice issues related to homosexual men, then? Not in my experience; social justice folks are generally entirely too inclusive to talk specifically about #gay or #lesbian anything. I've never seen a post about gay rights specifically tagged as #gay. Maybe "#gay rights" (that's a separate tag; Tumblr allows spaces in them) but not just #gay. [On the other side of the social-justice fence, notice that #lgbt is still a working tag. http://www.tumblr.com/tagged/lgbt]
So what was getting tagged as #gay? I would guess (I never saw their content streams, but it seems plausible) that Tumblr eliminated these two tags in particular more for their potential for use in hate-speech or in "outing" people. I would bet (real money!) that posts were getting reblogged and tagged #gay and #lesbian for entirely malicious reasons, and Tumblr was often having receiving requests to "de-tag" the reblog so people couldn't find their post through it, somewhat like requesting to get your name taken off someone else's photo of you on Facebook. Imagine if you typed "gay" into Tumblr's search box, and the first result was a picture of your face! [I don't think Tumblr actually had a mechanism for resolving these de-tagging requests, but it was still likely a high-traffic request.]
I'd bet (again, real money) that we'll see other high-potential-for-hate-speech tags disappear. In fact, they might already have, and it's just that no one has thought to look. Anyone want to think up some tags to try, and report back any that "should" have posts but are completely blank? Or, on the obverse, anyone with actual knowledge/anecdata of what #gay and #lesbian did contain before Tumblr blocked them out?
>The reason you see innocent tags like #gay being blocked on certain platforms is that they are still frequently returning adult content which our entire app was close to being banned for.
