As a retired tuner and player technician, I can say that any piano that
I ever tuned which had been treated with a pin tightening agent, made the
pianos very difficult to tune due to a certain amount of sponginess that
the chemical created in the pin block.  It was sort of like tuning a
piano with pins set in bubble gum.  It made the pins difficult to "set".
The familiar "jump" in a tuning pin, that only piano tuners are aware of,
is gone.

I have seen pianos that may have had the chemical applied in a sloppy
way, causing corrosion and destruction on the coils wound around the
tuning pin, and even corroded tuning pins.

This pin "dope" may have been an earlier version, but I saw so much
damage from it, over the last 40 years,  I never considered using it.
Modern versions may be different, but if I had a valuable piano, I would
not want any chemical used on it.

Bruce Clark¶
Tuner from 1946 to 1996