The VOIDRUNNER'S CODEX is LIVE! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
As far as I know (which admittedly is little since I don't own Tome and Blood), nothing. Rogues aren't kept from taking Hold The Line just because it's in Sword and Fist, are they?
Though I'm not sure why a Divine caster would want Extra Spell...
AFAIK, nothing prohibits divine casters from taking those feats. The feats might not do all that much for divine spellcasters, but they can be taken by them.
If someone's divine caster wants to take these, I see no problem with that.
By gearing each of the Class Supplement books to two classes it gives the impression that only those two classes are eligable for the new feats and prestige classes, but in reality 3E by it's very nature is very flexible and there should be lots of overlap.
Also, Extra Spell really only makes sense for sorcerers and bards (and for shugenja, if you count OA classes; also, for a few prestige classes that can know only a limited, fixed, amount of spells per level).