I don't think that guy works for Microsoft, he wouldn't know if it is 720p, he's assuming. I've seen him around a lot, he joined around the time of the Xbox One reveal. Never seemed like an insider to me.
EDIT: Seems it isn't just that guy. Wow. Holy shit Microsoft fucked up badly if fucking CoD can't run at 1080p. It's fucking Call of Duty. Now I'm wondering if developers are just not willing to optimize the S-RAM, or if the Xbox One is really that weak. I just... can't believe CoD will be 720p on Xbox One and 1080p on Playstation 4. (But then again, to be fair I don't think the resolution will be different between Xbox One and PS4 on any other Multi-platform title.)