[Ron6519]

The link you gave is for people who do not want to redo sheetrock or flooring. It's not very solid.
I either open the floor or the ceiling below and drop the newel post into the recess and bolt it to the framing member.
If you have to repaint, you repaint.
Ron

 

[Just Bill]

What ron said, if you want it to last.

 

[gma2rjc]

Mine is secured to the floor with a metal fastener under the post. It has never been solid, not even when it was installed.