Frank Cho seems to work best when there is plenty of room, and of course a "pin up" page in a comic is about as much room as you can get with the medium, which is even better than cover space since that is usually hobbled by demands for bar codes, logos, company information, pricing, etc. (Though Marvel Comics, aka "Marvel Worldwide Entertainment" hardly has logos on their comics at all, instead plain helvetica capital letters. No nuance or creativity in that approach, it's as if the 'logos' were meant to be scanned by post office computers or something equally mechanical.)
Valkyrie faces a harsher dilemma in New Ultimates #5 than the one here shown in Jeph Loeb's script for New Ultimates #4.