I feel for the officers in the tube station, but this appears to me to have been a badly planned operation with poor C3. If, charges are bought against the officers on the ground, then those responsible for the command and control should not only take responsibility, but IMHO be charged with the same offences.
As for Blair falling on his sword, as I understand he did nothing to dispel the "barrier jumping / winter garb / acting suspiciously" stuff that was spouted by the Met's own PR machine, until he was forced to, and for this, he should do the decent thing.
If nothing else, this awful situation at least brings into the public domain the issues of having to make split second life and death decisions, with poor resourcing, poor C3, a cynical media and HMG distancing itself from any responsibility. Sounds vaguely familiar.