^I think in fairness, he wasn't forgetting Tennant, but wasn't counting him as a Scottish-accented Doctor, because Tennant didn't play him with a Scottish accent. If Capaldi uses his own Scottish accent (and we don't yet know that he will), he will be the second actor to do so and the first to do so since McCoy.
I'm Irish, so I'd have to yield to our English and Scottish posters on this one, but to me, for the most part, Tennant's DW accent sounded convincingly English and not at all Scottish. But English and Scottish posters may say otherwise.
Tennant sounded English to me. Probably from the east end more than anything.