This response is based on the information provided. We suggest you discuss with your contracting team, program manager and/or legal department as appropriate.
In general, the PWS is a government document whether developed by the government or by an offeror in response to a Statement of Objectives. As such it is not proprietary. While we would not post them on the internet for no good reason, we would need strong justification to withhold a PWS if we received a FOIA request for it. It should be available to anyone associated with the program in the government or the contractor program team.
Unless it is classified or has some other legitimate security designation, it is safeguarded in a routine manner.