Did Speer discontinue this loading? I would love to a acquire some for a defense load in my .357 Revolvers.

That loading is still listed on the Speer website.
https://www.speer.com/ammunition/gold_dot/
However, it says currently unavailable.
Likely what that means is they are busy loading more popular ammo for semi automatic pistols.
Don't forget the millions of rounds they load for .gov contracts.
Someday, the ammo world MAY return to somewhat normal.
But that won't be today, this week, or this month.
Buying primers today is somewhat of an indicator.