To be clear, UA's stated policy contains the DOT-allowed 7-day exclusion (for a couple of years) but with just one exception posted on FT, multiple people have reported UA has not exercised the option even for travel day bookings that were cancelled. However, UA could institute this at any time without warning.

The one exception was a booking made at the airport and cancelled shortly afterwards after clearing security -- the OP admitted on FT there was no intent to travel, so UA may have a way to flag certain cases. The OP did not try to challenge the cancellation fee.