OK, seriously, those who actually care about this shit should just assume that a quick aesthetic surgery was a part of Section 31 fake identity package.
In the 23rd century, changing one's appearance shouldn't be much more difficult than changing a name. Heck, they can probably do it in a matter of minutes.
Heck, Kirk had himself surgically disguised as a Romulan in "The Enterprise Incident," an Orion was surgically transformed into an Andorian in "Journey to Babel," and a Klingon was surgically disguised as a human in "The Trouble with Tribbles."
So it's canon!