On a more positive Note the Inquisitor could be a really smart guy. Figure out why Cpt. Titus is warp resistant & hopefully untainted. Speak to The Ultramarines about this matter. And figure out how usefull he is. He would be the bain of chaos sorcery.

Or he could have realised that the Blessed Power Armour Titus wore included gauntlets. Titus didn't touch it, his gauntlets did.

Pallomides said:

Or Titus could be corrupted and spread his taint to Emperor knows how many people and perhaps even damning the entire Ultramarine Chapter to Chaos because the Inquisitor was to soft. I think that when dealing with Chaos the smart thing is to be safe rather than sorry.

I think thats what makes the 40K world grimm. Demons & the warp are real and innocence proves nothing. Sending people to the stake is often the only viable option.