I usually pretend to have the escape alone objective any time I'm traitor. I can pull it off most of the time, the real trick is making sure people DON'T realize you're stealing the shuttle until it's already arrived. I've pulled this off even with the new shuttle bug (I have to say, it's really nice knowing the shuttle won't just take off suddenly now, maybe when they fix it it should just reduce timer to 1 minute instead of 10 sec).
The trick is to realize that doors can be completely disabled (Although they can still be destroyed with the right tools). Disable the escape doors, and now all you have to do is worry about someone getting in through space. However the number of hardsuits on the station is much lower than the number of suicidally overconfident assistants, so it certainly helps.
Advanced traitors could try to get rid of some of those hardsuits to lower the amount of opposition available.
It's pretty illogical, but whenever someone says to stay away from escape, if I have any ability to fight, I'm going to try to get on that shuttle...
Not quite. By far the easiest way to get into a sealed escape is to burn through the wall from the closet just below it. If you've got any sense all it takes is a splash of thermite, and the poor man's version only requires a welder and wrench. Or if you're me, a cap bomb dropped outside Escape and a hardsuit to clean up the mess afterwards.
Don't be silly. Sealing off escape isn't worth your time. You seal off the doors that lead to the shuttle. Meaning yes, you will need to board the shuttle from space. But so will everyone else, and you have a head start before they realize those doors aren't going to work.
Maybe sealing off escape isn't a terrible idea as an initial measure, but there are a lot of regular walls leading in, so someone with a welder and wrench, or thermite as you pointed out, can easily break in. And if you make it obvious you're trying to seal escape, people are more likely to grab hardsuits and be ready to break into the shuttle from space. But if you can do it without people noticing, they'll waste that time breaking into escape only to find the doors out to the shuttle don't work.
Standard door destruction techniques will still work of course, but disabled doors are much harder to get rid of than walls or windows. This worked fine for me last night, I laughed for three minutes as the crew desperately tried to unbolt the doors, then the shuttle took off without them. If you could e-mag the shuttle again, this would really be too easy, in my opinion.
Does thermite work on doors?
EDIT: I suppose a bomb might work, but it wouldn't make any sense for a non-antag to explode escape and some of the shuttle with a bomb just to get to the shuttle, when doing so would probably render it unusable for most of the crew. A good idea if there are two different antags trying to steal the shuttle though.