No.  If it was never their Principal Residence AFTER it was their non-principal residence, Nonqualified Use does not apply.  Or to phrase it another way, if during their ownership the only time  it was a non-principal residence was at the 'end' of their ownership, just treat it as normal (Nonqualified Use does not apply).

That is one of the reasons I asked if it was their Principal Residence from when they bought the home until it was converted to a rental (to check if it was ever NOT their Principal Residence, other than at the 'end').

Does that make sense?

[EDIT:  The purpose of it was to prevent people from having a rental property then moving into it for two years to exclude all of the gain (besides the gain due to depreciation).  That is why making it their Principal Residence AFTER triggers the Nonqualified Use.]

If it was their Principal Residence AFTER it was their non-principal residence, Nonqualified Use may apply.  However, Military (up to 10 years) and Temporary Absences (up to 2 years) are also ways to get 'out' of Nonqualified Use, but are less common.