Still...I was pretty sure that not many legitimate astrophysicists believed that time travel is remotely possible outside of quantum scales, and that there's an awful lot of other physical laws that specifically say it doesn't work that way. For me, that's enough to dismiss it out of hand; that might be incorrect judgment on my part. When more evidence pops up, I'll reconsider, but let's just say that any paper claiming perpetual motion gets filed to the same place in my mind.
From my reading, there aren't currently any explicit laws that prevent time travel, however all known methods require such ridiculously complicated methods to achieve (things like infinitely long, infinitely heavy rotating cylinders etc.), that it's considered impossible by most sane people. Pretty sure Hawking's been trying to prove something that states causality can't be violated, but what I've seen of his arguments have basically boiled down to "It's silly, it shouldn't work, so it doesn't work". That being said, I read it in New Scientist, which isn't always the most factual source.
Regarding YEC's, I love their arguments. It's so cute, like watching a one legged elf try to outrun magma. I pay my bills doing geochronological work, so I have a rather large list of things to slap them in the face with.