Just to update anyone else on this I finally received a reply from the Pa. Dept. of Revenue (I submitted the question December 10th). They confirm that loans forgiven under PSLF are taxable as the forgiveness is linked to employment.
"The student loan amounts forgiven under the Public Service Loan Forgiveness are subject to PA state income tax. The loans are only forgiven for those individuals who agree to take a public service job. PIT Bulletin 2009-02. https://www.revenue.pa.gov/GeneralTaxInformation/TaxLawPoliciesBulletinsNotices/TaxBulletins/PIT/Documents/pit_bulletin_2009-02.pdf
"The student loan amounts forgiven under the Public Service Loan Forgiveness are subject to PA state income tax. The loans are only forgiven for those individuals who agree to take a public service job. PIT Bulletin 2009-02. https://www.revenue.pa.gov/GeneralTaxInformation/TaxLawPoliciesBulletinsNotices/TaxBulletins/PIT/Documents/pit_bulletin_2009-02.pdf