It is very common (at least in my area--SC) for multiple offers to be present on Freddie Mac homes.
We don't have POS inspections, but if I were you, I would submit my highest and best before the HAB period expires, but in the meantime I would get in touch with the listing agent to see if Freddie's 10 day inspection period allows for leniency for the POS inspection. We don't have POS inspections here, sorry I can't give me concrete advice. I would say that the listing agent would have probably run into this before, and they might very well be your best source of "been there, done that" experience.
In my experiences with Freddie, they have been fair to work with, as long as you know the hoops to jump through.
Yes, the contingency for financing would be another "out," BUT it has also been my experience that Freddie's reply to your HAB could take another 1-3 business days. If they choose to address your offer, they will prepare addendums, which will take another 1-3 business days.....so the POS inspection could very well happen within that time frame. Those extra days, if nothing else, will in effect draw out the process and "lengthen" your inspection period.
Good luck.