Additional Reservation Cost doesn't apply to auras of type Purity of X

Too lazy to make screenshots to prove as it's incredibly easy to test.

I tried Malice, Discipline, Fulmination and Purity of Fire/Ice/Lightning.

Socketing any supports into Purity auras (i.e. Vitality II, Clarity II, Precision II etc.) doesn't add any cost, doesn't disable the aura and still grants the benefits of the supports.