The  PA 40 instructions sure sounds like you're correct....      -  Not likely that PS has the ability 'flip' the primary TP and Spouse....  @PATAX would know...   

Side note -- if any estimates were filed under 'Deceased' primary TP  SSN you have to file a form w/ PA to have them applied to the Sp SSN or you'll have a mess.... 

PA40 Instructions.

If a joint return is filed and the taxpayer, spouse or both are
deceased, complete the married filing joint oval, the deceased oval
and the spouse and/or taxpayer ovals as well as the date(s) of death.
The surviving spouse should complete the name and Social Security
number section of the return as the primary taxpayer on the return.