I do not believe that Marvel hired him for his writing skill. I think they hired him because his name on a comic sells a lot of copies. Presumably they were aware of his work at DC and knew he was likely to screw around with continuity and established characterisation, but that was less important than the dollars. They deserve to be taunted for it.
But I do try to keep my cynicism down to those that deserve it. You can't help second guessing upcoming events that have been trailed, but unless I have good reason to fear the worst (like it's written by Jeph Loeb or Frank Miller*) I try to wait until the comic arrives before passing an opinion stronger than "I'm looking forward to it" or "I'm not looking forward to it". The only times I've addressed Batwoman was to comment on the behaviour of the media to the announcement, and I haven't said anything about the news that Jodi Picoult will be writing Wonder Woman because I haven't read any of her previous work and have no idea what kind of job she will do. It's good in theory that a woman should write the title, but what that will mean in practice I have no idea. So I'll just wait and see.
One of the things that got people a bit exercised recently was Joe Kelly saying that the only reason he agreed to write Supergirl was that everyone else turned it down. This has led to a lot of speculation that the horrible mishandling of the big relaunch of the Girl of Steel has turned her from Hot Property into Unwanted in a very short space of time.
I see shadowy figures walking the streets of the internets yelling "Doooooooom!! Dooooom!!" but in fact it's another case of Brainiac's enlargement ray and a hill of moles. I first got suspicious when I saw a post from Gail Simone saying she would have been interested but she hadn't been offered the title. Now I know I'm biased, but if I was DC editor in charge of matters Supergirl, Gail would be high on my shortlist of writers to approach.
So then I looked up the source. The quote is from an interview last month at Wizard. What it actually says is:
With Rucka departing after one issue, Kelly claims he got the gig because of his helpful nature.
"Everybody else said no," Kelly joked.
The "Kelly joked" bit seems to be forgotten. At the very least it suggests that he is exaggerating when he says "everybody". In fact it could just mean that the first couple of choices for writer turned down the gig because they are everyone's first choices to write their comic and they already had a full schedule. The impression given by the interview is that they were in a bit of a rush because Greg Rucka was leaving earlier than expected (for unspecified reasons) and they needed someone at short notice to keep it on schedule. Hence Kelly helping out. There is no suggestion that the comic is any less popular, it was just a joke that got taken way too seriously.
*My response to hearing that Miller will be working on the upcoming Spirit movie was "If he turns Sand Serif into a ninja I will not be responsible for my actions."