I don't see one shred of evidence that McVeigh was driven by the desire to kill and hurt and that his ideological beliefs were only rationalizations. (Would make it so much easier if he were, wouldn't it?) But of course I believe McVeigh was wrong and Blake right. As Alison said, Blake's actions "feel" different. But why?
How about this: McVeigh committed an act whose direct, inevitable, immediate consequence was mass homicide. Blake's destruction of Star One would have caused massive disruption of climate, food production, etc that may well have lead to massive loss of life indirectly and over the long run (or may not have), but by bringing down the Federation may also have saved more lives than it cost (in the long run). It's not about "real life" vs. "fiction", IMO. If Blake had thrown a bomb into a building full of innocents (children or not), I wouldn't be defending him.
Sondra