I have sent my application for OINP; however, I too have used PF as POF. Before using PF as POF, I had emailed OINP asking if PF can be used as POF and here is what they had to say:
"Thank you for your inquiry regarding the Ontario Immigrant Nominee Program - (OINP).
Funds that are not readily available on demand would generally not be acceptable for your settlement in Ontario. Therefore, if the said funds are those that cannot be liquidated on demand, for example, funds invested in stocks, bonds, retirement investments, etc., it is not acceptable.
However, if the said funds are those that can be liquidated on demand, then it may be acceptable."
Therefore, if you still want to take a risk. I would suggest to accompany your PF statement with a letter from your employer/responsible officer stating that you have access to the fund on-demand.
Hope this helps.