Recent articles claim that the suspect emerged from a "block of flats" that was under surveillance. That does not sound like he came from a specific address being watched. Another poster suggested that this guy may have been a suicide terrorist whose mission was to make the British appear to be anti-Muslim. He may have succeeded if that was his mission.
Another poster suggested that London weather is similar to San Francisco. The conditions in SF can go from sweltering to chilling in half an hour due to coastal fog. Wearing a jacket is prudent.
I spent a year and a half in the tropics in my youth and was also a smoker. I wore a jacket at all times for years after returning home. People raised in India would be quite accustomed to warm weather and intolerant of temperatures in the low seventies.
If the details regarding this suspect running away and jumping the turnstile don't hold up any better than the address, we're probably looking at a bad shoot. Who's to say that terrorists would not plant a false address just to lead to such behavior? Perhaps the address was of a person who refused to get involved in such matters and planting his address was payback.
There's a certain level of intelligence and awareness required to continue living. Was he completely clueless as to what was going on around him? If so, he lost his life out of sheer stupidity. Nature doesn't owe any organism a living; either an organism uses its faculties to help it survive (uh, when the police order you to stop a day after several terrorist attacks, stop!) or else it gets dispatched into the wastebin of history.