I would not know, as I haven't yet tried out any of the MEs yet. However, I assume Kaiden was created to be SGRable? Corso does not seem to have been, and we *are* talking about BW-Austin, not BW-Edmonton (which is responsible for ME). Unless corso already had an entire SGR romance line built into the game, just not turned on, then it's unlikely that it would be rebuilt from the ground up at this point, just due to the costs involved and the severe downturn of the population since release limiting the ability to focus so many resources into rewriting one specific character's arcs.
Quite the contrary, Kaidan (have to correct myself here, it's an A, not an E) was created to be the exclusive male romance character available to FemSheps in Mass Effect. He's the quintessential male character through the first two games, but in ME3 if you set things up correctly, he will make a pass at a Male Shep.
You're thinking of Cortez or Traynor (both of which were masterfully done by the way) for characters meant solely as SGRs. As for Austin vs. Edmonton, I don't think it's a manpower issue, it's a time issue. If they're really committed to bringing SGRs in for companions (which Jeff's little snippet makes me considerably more certain of), it's then a question of how long it will take. Mechanically speaking, the reworks they're already going to have to do to accomodate max-level toons is going to dwarf the time needed for specific tweaks and rewrites.