R241 Sorry, I've never been a Larry believer! Always been more sure of Harry/Nick.
R243 I understand what you're saying, but if we go along with the idea that they want a slightly older audience, Tumblr won't be so relevant. I'm 23 and no one I know uses Tumblr. I have pointed out to some the Larry Tumblr blogs as a bit of a joke and many of them have simply rolled their eyes and repeated the "delusional fangirls" schtick. They either believe Harry is straight, as per the tabs, or they believe that there's something going on with Nick Grimshaw (less of those, though).
There are a lot of hardcore fans who use Tumblr and Twitter; however, if you look at the amount of followers they all have on Twitter (5 - 6 million) there's only a small percentage of those who are "obsessed", so to speak, either with being with the boys themselves, or who believe in Larry and therefore probably use Tumblr for that reason specifically, rather than the far more saturated One Direction tag, where much of the Larry stuff gets lost.
The rest probably buy their music, read interviews and articles in papers and online, watch interviews on the TV etc. but don't go much further into the more fandom aspect of it. If you asked them about "Larry", they'd either have no idea about it, cite it as a bromance, or say "oh that thing the crazies talk about online".
Now, as you say, of course the PR and management have to regulate it, but never has there been a case (and do correct me if I'm wrong), where a fandom ship has become entirely mainstream. Larry borders on it, but the likelihood of it happening, where those who don't use Tumblr start getting into it as a real relationship with conspiracy theories, are fairly slim.
Also, I think their tactics would be far more subtle. Yes, if you are on Tumblr then you are aware that people have been speculating about Eleanor and Louis and what's missing, therefore you are aware that those pictures have come out to combat that; if you're not on Tumblr, or not tracking certain tags, you'd just assume it was a leaked photo.
One anonymous message - one that didn't even go viral and which was very blunt and crass in what it said - is not subtle or effective.
I'm not arguing that they don't use Tumblr and have no interest in the fans there; I'm just arguing that it's probably not a huge panic issue to them and that the way they use it wouldn't be quite so blatant. If they read these things, then they know that the fans are very aware of "management moles" and leakers who plant information; they'd have to go a bit more native if they were serious.
Alternatively, you could argue that if they're using Tumblr more intensively, then there's a higher likelihood that they're pushing Larry to keep these girls interested, because the fever never dies down. Maybe they have a Larry blog?
To be honest, I don't know how Tumblr works all that well and I don't know anyone who does; I mainly use it to look at pictures of Harry. So I could be way off base, but I think if they're trying to plant ideas to the fanbase as an entirety, it's not going to be through anons on the Larry tag.
R246 I don't think Harry looks any younger than 18?! And I don't think people have no sympathy at all because he's a young boy/possibly gay; my mum was 17 and my dad was 29 when they met. Funnily enough, no one said he was grooming her and they're still married today. The age gap doesn't immediately plant them in the same category as others who have been predators or dangerous.