For me, it's not so much whether he is faking it. It's really whether anyone can accept a redemption arc for Doom after the acts Marvel had him do in the past. If continuity doesn't matter (and I am increasingly under the opinion that it may not) then Doom very well could have had a change of heart.
I think an redemption arc is a natural direction to go. Doom generally walked the line and was often depicted as somewhat noble and fair. But he has also been depicted as a mass murderer, child abductor and a necromage. So his arc to being "good" will be steep for many long time readers.
Aside from that, I could see Doom as potentially being a very interesting anti-hero in these times. He's the most powerful non-mutant in the Marvel Universe (technically).
I don't think Doom's version of 'good' is the same as the rest of the Universe's version of good. So to him it might be 100% authentic, but to anyone else it might be different.