Seriously, I keep getting knocked out of my meditative state just by the jerk of the train starting to move, I guess...
I don't see any reason why it should do that. :|
I think Cirnots is talking about the Subway not a conga line/train of glitches, which I believe you can meditate while following another glitch. But it does make sense that if the entire "room" you were meditating in suddenly and quite noticeably jerked that you would probably lose focus for a second.
I dunno... I sleep. err... meditate on the train during my commute all the time IRL, besides, how much of what happens in Ur makes sense? nibbling pigs? squeezing chickens? and from a gameplay perspective it makes sense to expect meditation to work on the subway... The standard throughout the game seems to be 'no user action = no interruption of meditation'..