Two-Weapon Defense and Shield Feats

[7th son of sons]

Does the Two-Weapon Defense Line, which grants a shield bonus to AC, allow you to use feats such as Active Shield Defense, Shield War, and other feats that require the use of a shield? If they do not, would it be overpowered for the two lines to work in tandem? I.E: Would it be fine to Houserule that Shield Specialization can be used to Improve on the Shield bonus from Two-Weapon Defense?

[Seerow]

They do not work, no. If that's the route you want to go you're better off using a spiked shield for the offhand, and ignoring the two weapon defense line.

I don't think there's anything overpowered about letting them work together if you're houseruling, but that's a ton of feats being invested for a marginally higher AC (and one that would be outclassed just by grabbing a buckler and casting magic vestment on it)