I am a bit confused by the existence of the Jonas Phillips letter
commenting on the language used in a clause in section 10...
Was the convention not held in secret?
And if so, how did Jonas Phillips know the details of the content?
Oath taking in PA had been problematic from the beginning of the colony. Quakers who controlled the government until around the French and Indian Wars refused to take oaths. Unless some alternate provision was made for them in the PA Constitution, they could not participate in government either, along with Jews.
In some corners, the prohibition of religious oaths was used as ammunition against the Federal Constitution. Luther Martin for one, railed against it at the MD ratifying convention.