Due process is a judicial process, not a legislative one
Apparently SCOTUS disagrees with you!
The court said Congress had the power to modify the rules, which it has done several times -- such as gradually raising the full retirement age over time.
The Supreme Court never said "due process" is a legislative process, you're full of shit
Here is what SCOTUS said:
Congress can change the rules how they see fit, as long as they follow due process.
Show the actual quote because "due process" doesn't make sense in that sentence. Due process is a judicial process, not a legislative one.
Note the fifth and fourteenth amendments guarantee due process of JUSTICE
Due Process Clause - Wikipedia
If you can legislate due process, that would mean that congress can pass a law saying to kill every first born son because you cannot lose your life without DUE PROCESS. You're arguing their passing a law is due process.
Why after going back and fourth are you not googling this? Lazy or just indifferent to knowledge?
TO ENGRAFT UPON THE SOCIAL SECURITY SYSTEM A CONCEPT OF "ACCRUED
PROPERTY RIGHTS" WOULD DEPRIVE IT OF THE FLEXIBILITY AND BOLDNESS IN
ADJUSTMENT TO EVER-CHANGING CONDITIONS WHICH IT DEMANDS. SEE
WOLLENBERG, VESTED RIGHTS IN SOCIAL-SECURITY BENEFITS, 37 ORE. L. REV.
299, 359.
IT WAS DOUBTLESS OUT OF AN AWARENESS OF THE NEED FOR SUCH
FLEXIBILITY THAT CONGRESS INCLUDED IN THE ORIGINAL ACT, AND HAS SINCE
RETAINED, A CLAUSE EXPRESSLY RESERVING TO IT "THE RIGHT TO ALTER,
AMEND, OR REPEAL ANY PROVISION" OF THE ACT. SEC. 1104, 49 STAT. 648,
42 U.S.C. SEC. 1304. THAT PROVISION MAKES EXPRESS WHAT IS IMPLICIT IN
THE INSTITUTIONAL NEEDS OF THE PROGRAM. SEE ANALYSIS OF THE SOCIAL
SECURITY SYSTEM, HEARINGS BEFORE A SUBCOMMITTEE OF THE COMMITTEE ON
WAYS AND MEANS, HOUSE OF REPRESENTATIVES, 83D CONG., 1ST SESS., PP. 920
921. IT WAS PURSUANT TO THAT PROVISION THAT SEC. 202(N) WAS ENACTED.
WE MUST CONCLUDE THAT A PERSON COVERED BY THE ACT HAS NOT SUCH A
RIGHT IN BENEFIT PAYMENTS AS WOULD MAKE EVERY DEFEASANCE OF "ACCRUED"
INTERESTS VIOLATIVE OF THE DUE PROCESS CLAUSE OF THE FIFTH AMENDMENT.