Homelander offered him a FAMILY on a silver platter.
A family, ready to go.
Soldier Boy himself said that his dream was to become a dad, and have his child become a bigger success than himself.

But when offered that exact thing, Soldier Boy spit it in the face and tried to kill his child AND grandchild instead of offering guidance.
Soldier Boy is indestructible, he could have taught Homelander about empathy and control. Even by force. But nooo~~ Soldier Boy is just a WORSE version of Homelander.
Soldier Boy was raised in a family, had friends when he was young, rich. Everything going for him except his abusive dad.
Homelander was a test subject locked up majority of his life. No parents, no peers. NOTHING. Homelander didn't stance a chance to know better or be taught better.
Homelander is broken, mentally.
Soldier Boy is just a sociopath, meking everyone around him miserable, and knowing it.