Why don't I just clear this up for everyone right now

I'm assuming the OP is flying on the refurbished 764 intl.

DL does not allow anyone including medallions to preselect exit rows on international longhauls (the only exception would be the domestically configured 764). When they first released the seatmaps for the reconfigured 764 intl, they forgot to block out the exit row seats (I noticed this a couple of months ago and brought it up on FT).

I'm going to assume that DL simply noticed the mistake and subsequently blocked those exit row seats and kicked everyone out.