I have to tell you that I have NEVER heard of a company dropping HS for Master! I have heard of HS dropping Master dealers though, two completely different types of sales and company philosophies.
I don't think there is a lot of love between the two so my guess would be that HS played hardball telling the dealer to get rid of Master or they were done and the dealer either did not like being dictated to from the manufacture (That's would be how I would take it) and/or did not represent HS like they thought they should be in the market....