not to defend what that driver did, but it's possible they simply weren't paying attention, then realized "oh crap that's my exit" which was of course quickly followed by "f--- all you other cars, i'm taking this exit right now! you got brakes, use em!"
so they might not have PLANNED to cut you off, but they certainly weren't considerate once they realized the situation.
personally i learned to drive in houston. here, if you use your signal before you make a lane change, most people will speed up to close the gap so you can't get in front of them. cuz a lot of houstonians are just special like that. i generally just keep coming over anyway, especially if it's really obvious that they just floored it to prevent me from coming over (ie: i am going at least 10 mph faster than you which was obvious when i passed you, but now all of a sudden you're catching up to me even though i never slowed down? gee that's not obvious at all...)