That box is being checked by moderators when reviewing the submission.  Because of the volume of wallpapers we receive every day, we are more critical of what makes it to the public gallery.  Work that we, as a team, feel does not meet that bar, is placed on the user's personal page.  It's still publicly accessible, it just doesn't appear in the main gallery list.

Resubmitting your work repeatedly will not change this flag.  We have notes on all skins that are moderated so we know when an item has been flagged for personal page only.