According to the section on diet in the bill starr routine if a trainee commences the program with a "pretty big margin of bodyfat" he already has a caloric excess so he can build muscle(and lose fat) by just eating at maintenance.

Is that so?

Reference;http://www.geocities.com/elitemadcow1/Topics/Diet.htm

Within the right context of a generally untrained individual starting at a higher BF% (>=18%), probably, or at least maybe. :)

It's a general lack of context, and ignorance to the notion you need to try things out for yourself in the real world to truly find out what's possible with your unique body, that gets people confused about when you can expect to possibly add muscle and lose fat at the "same time".

Yeah, the idea goes to recomping.