Hello Kenyatta,
Your question is a bit interesting, but I will give it a go and hope it helps you.
First, PEMCO, etc. are legal entities/organizations that HUD has legally contracted with to market, advertise, sell, etc. the properties that are assigned to them. Next, because of that alone, they are right regarding the "equitable interest" issue. Now, unless you are the assigned-agent, there MAY be some restrictions on anyone actually marketing or advertising a property as if they are the assiged Broker/Agent. However, you can (not for selling purposes) forward the info. to someone for general information purposes-only.
Take FSBOs for example: If you wanted to advertise them somewhat like PEMCO does for HUD, than your best option or strategy is to do an "Assignment" (a simple one page legal-document) which gives you the "legal right" to advertise, market, and/or sell the property on behalf of a property-owner (in the case of a FSBO sytle of transaction-for example).
Note: If a property is under-contract with a Licensed-Broker or AGent, than you would have to wait until that contract expires with the Agent/Broker to protect your interest, position, or to profit in a FSBO-deal or a property that you may want to market for someone else (e.g., FSBO, Wholesellers, etc.). Just be sure to always ask them for the "right to market, advertise, sell, etc." The Assignment process works much better because you can control the transaction until the expiration date--or renew it if you and the seller are in-agreement with continuing to market it.
Hope this helps you,
Much Success As YOu Invest