Yes you can still major gordo a home world, preventing that would require changing the code and lets be realistic stephen hasnt done that in.........lets see........*takes off shoes to start counting........
I was under the assumption that homeworlds were unable to be gord`d after say late 2004ish... due to the very fact that there were player with 80 - 130k homeworlds that gave them an unfair advantage. There was a player in my fed at the time (forget his name) that had one such homeworld. I believe they were grandfather`d in... but I doubt they are still around.
Tranq is correct they are mainly used for land increase on non paid race home worlds since they cant be taken or killed off. If I remember right the land increase is 2x that of a minor gordo, but since it takes 2 minor gordo to make its not often used for much else. Other arti formulae maby?
It`s not worth making typically. The main benefit being that you can use it on your homeworld (I think?), but I don`t think the land gained is beneficial based on how many minor gordos it takes to make one.