|Yes, because they killed him, he must be guilty of something.
No, not at all.
But if you look at this from the start, and remove the emotions, you'll see that the officers hadn't a choice, really, considering what had happened on 7/7 and 7/21.
It's not at all hard to detonate something if you've got 4-5 people on you, not if you manage to get your hands on a grenade pin, a detonation device, or trigger of some sort. And lots of that stuff can be concealed elsewhere - not just in a jacket or around someone's middle. Recall Richard Reid, the Shoebomber. What if they'd become more sophisticated, and were able to detonate a shoebomb not with a match but with a triggering device, in the jeans pocket, or from a chain around his neck? Or a stick of C4; not very large (maybe 2 inches) concealed in someone's pocket could be detonated by a cord trigger attached to someone's finger...or something along those lines.
When you really think about it, just opening someone's jacket is NOT going to be definitive...
As for an innocent man losing his life, that is terrible. But had one of the methods been employed, and the man managed to make it to the Tube, and detonated another bomb, that would have been far more terrible.
Other thoughts to consider.
1. Why was he under surveillance? Of what was he suspected?
2. Why was he searched several times?
3. Why did he run this time and not the other several times he was searched?
4. Why did he run towards the Tube and not a park, mall, or store?
If I had a suspect under surveillance, suspected of some sort of nefarious activity, having had reason to have searched him several times (and make no mistake; that was in the briefing packet or else why would they know to call to him and want to talk again...), and he takes off, goes to the Tube, and is not naked and barefoot (therefore I don't know what he has concealed...), I'd most likely shoot him, too.
Does it suck? Most certainly. Do I feel sorry for him? Of course. And I feel sorry for the officers who had to make life and death decisions in heartbeats and not over the course of several days, like we are, armchair quarterbacking their decisions.
Of course, this is just IMO....and yours may be different. But wear the officers' shoes for a moment, and really try to see what they were faced with...and you might come up with other opinions.