Holder of what?
Language from a Mortgage Backed Security
Depositor is generally engaged in the business of serving as depositor of one or more trusts that may authorize, issue, sell and deliver bonds or other evidences of indebtedness or certificates of interest that are secured by a pledge or other assignment of, or represent an interest in, mortgage loans and other mortgage assets. The Depositor is also generally engaged in the business of acquiring, owning, holding, transferring, assigning, pledging and otherwise dealing with mortgage assets.
Language from a Security Instrument (Deed of Trust)
20. Sale of Note; Change of Loan Servicer; Notice of Grievance.
The Note or a partial interest in the Note (together with this Security Instrument) can be sold one or more times without prior notice to Borrower.
"Interest in" is nothing but a Transferable Record whereas UCC 9 applies but Local Laws of Jurisdiction do not apply to Transferable Records, 15 USC 7003…
Most of the time when a "Holder" is discussed it means the Holder of the note.
The "Holder" is the entity that physically has the note and usually are entitled to enforce the note when endorsed in blank.
I'm pretty lost with what you posted, I don't see the relevance.
Nothing in the PSA helps a borrower. You are not a party to the contract and can't enforce the PSA or complain about it's breach.
Maybe you could explain a little more.