If I understand the genetics of the 'Platty Daddy' right...
Platty Daddy x Normal gives you:
Lessers 100% het 'Hidden platty gene'
Normals 100% het 'Hidden platty gene'
since the Platinum or 'Platty Daddy' is a Lesser which is homozygous for the hidden Platty gene... right?
This is more or less right. From what Ralph Davis has said, technically all Butters and Lessers can make "Butter Daddies" and "Platty Daddies" as long as the "Normal" they're being bred to carries the Hidden "Platty" gene.
So in a Platty x Normal you get:
Lesser Platinums
Normals 100% Het. "Hidden Daddy Gene"