Did you even read what you linked to?
This article (which was mostly completely general until the end and therefore practically useless) said that each state taxes the player based on the game played there. And NY will only charge tax based on your so-called duty days. If you're in another state and preparing to play in another state, obviously that's not your duty day.
This is why my link showed the breakdown. If what you're saying is true, the effective tax rate shown in my link of 8.71% would've been 10.95% (Jersey's rate). Why? Because after you offset the Jersey tax by the amount you paid to another state, you'd be liable for the difference. So the rate would be 10.95% (that would make up the difference). Instead, we have much lower rates.
I said earlier that this is effectively the average of all the rates. I know it's not but I saw no point in getting into the complication of duty days. The main point is that your taxes are always lower if you come from a high tax state than the top rate in that state, and they are always higher if you come from a low tax state.