Your wrong taking advantage of a glitch is cheating....many game sites will ban players taking advantage of a glitch...like Runescape
A number of thoughts immediately come to mind. Here they are, in no particular order.
First, just stating that someone is wrong doesn't make it so. Second, in determining if something is cheating on this site, it's irrelevant what the rules or norms are at other sites. Standards or norms are determined by each site.
Now, one could argue that because it's defined as cheating on another site then it should be defined as cheating here. But it doesn't necessarily follow that taking advantage of glitch is always cheating because X site defines it that way, regardless of how many examples one could provide.
Additionally, I believe the principle at work here is "that which is not prohibited is permitted." There is no doubt that WGT knows about the glitch. But they have not shut it down, stated it's a cheat and should not be used, or sanctioned anyone (to my knowledge) for taking advantage of the glitch.
tl;dr: Just because a glitch is considered cheating somewhere else doesn't mean it's cheating here.