Quicken Power was written before Swift Actions were a thing
The text you see is how Quicken Spell used to read, since it was also written before Swift Actions were introduced (first in Miniatures Handbook IIRC). Quicken Spell was updated when Swift Actions were introduced, but Quicken Power, being from a supplement (the SRD did not yet exist and Expanded Psionics Handbook was no more “common” than any other supplement), was not.
The reasonable thing to do is to rule that Quicken Power should be read as the psionic parallel of Quicken Spell, and thus also use a Swift Action now that those are things. If you want to be extremely pedantic (or want to reject the introduction of Swift Actions for some reason), it’s a special Free Action that can only be taken once per turn (as Quicken Spell originally was).