I'm not sure the subject heading matches the FAA letter.

I read the letter as

"The Faa considers
service life recommended by the manufacturer
a non-regulatory requirement
for a chute that meets
TSO
TSO
TSO
and sold before service life was established.
To establish a new service life, the correct procedure is an SB."

Which brings up the case where
the manufacturer established a service life
before selling the chute.

It's not clear the letter applys to that circumstance?

The SOFTIE user's manual says that FreeFlite has established a 20 year lifetime. Assuming this is before sale, is it a binding reg?

It seems academic. I think I can replace a 20 year old chute.