Yes, it would, unless he always had that power.
I don't see the logic of why it wouldn't work.
And if it does, then that power basically makes you immortal. Killing you in the past, or preventing your birth, has no effect on your existence in the present day. THAT'S not fair! I totally wouldn't have approved that art of the power.
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)