Along the same vein, what if I masse the cue ball out of the kitchen to the center of the table without hitting a rail, then the spin draws it back into the kitchen contacting and sinking my object ball that was in the kitchen?
That is what I think the rule is talking about in regards to the cb crossing the head string. Similar situation from barroom rules for 8 ball. Say if the 8 is hung in one of the pockets in the kitchen and you are coming to the table with bih in the kitchen, you can shoot at the 8, but you have to kick out of the kitchen and back in, ie long table kick, or with the cb in the kitchen, kicking to the long rail with inside and coming back to pocket the 8 etc.