Agree w/ Aenea here about asking for a WC.
It is player's responsibility to sign up for tournaments/ask for a WC if they have forgotten.
Well, the player bears the responsibility for ask for a WC.
Then picks, made before to ask, it is necessary to ignore all.
Item 17.6 maybe such:
17.6 What if a player posts picks without commitment or WC?
His picks are not valid. After inquiry WC to make picks follows anew.