“As I listened to Mr. Gandhi putting the case for commutation before me, I reflected first on what significance it surely was that the apostle of non-violence should so earnestly be pleading the cause of the devotees of a creed so fundamentally opposed to his own, but I should regard it as wholly wrong to allow my judgment to be influenced by purely political considerations. I could not imagine a case in which under the law, penalty had been more directly deserved.” – Lord Irwin
The deal between the British and the Congress was established after much discussion. The initial demand was that ALL political prisoners be freed. This was whittled down to political prisoners not charged with violence. The British refused to budge on this point.
You also have to remember that at the time millions of Indians were suffering and farmers were dying, starving and their will about to break. The congress was almost all in jail, and Gandhi was desperate to get out of that situation where he was not the one suffering but India certainly was. Some would say his hands were tied.
Not to forget that Bhagat Singh also knew that he would be a much better influence to his movement dead than alive. He refused to "apologise" (obviously), and was actually searching for a martyrs death.
Plus, don't misread or misunderstand. I said the British considered Bose to be a terrorist. To Indians he was a hero.
The problem, however, with violence, is that you can be painted as a terrorist by those whom you attack. It was easy to paint Bose or Bhagat Singh (for the British people) as that.
Personally, as someone who was (still is perhaps?) hot-headed, and who has got into many fights because of a short fuse, I can easily relate to Bose or Bhagat Singh. I cannot imagine being persecuted, shoved around, jailed and ridiculed, and also keeping my "civility", or staying cool. That's an alien concept for me, and thus, perhaps why I respect the non-violent movement a little more - it seems a harder thing to do.
Remember this scene from Gandhi (the movie), where people keep walking to the gates of a salt factory and keep getting hit with lathis, while the women tend to the wounded, only for them to get back up and quietly be beaten again?
That visualisation -- of what I had only read before as boring history lessons -- made me realise that it took much more courage to do that than I could ever dream of having.
It certainly made me appreciate the contributions of the non-violent movement (which, as an uneducated teenager, I thought was non-violent because they were too scared to fight).