I Googled the school WhiteBelt referred to and read of their "Grand Master." I have not heard of Sensei Holubecki and could find no info about his lineage (perhaps I didn't dig deep enough, though it seems to me that credit and respect should be given to one's teacher on their website.) I find this odd. There are (way too) many 9th and10th degrees in Isshinryu, a situation that, IMO, is not beneficial to the system.
The lack of a unified organizational structure in the system, dating from the late1960's in the USA, has led to a plethora (finally got a chance to use this word) of "Grand Masters." Each splinter organization has their own 9th and 10th degree, and there are many splinter organizations. Not to say some are not actually deserving of such rank and title, but there are some I would not recognize as such. I don't know where Sensei Holubecki would fit in as I'm not familiar with him and his background, but lost track of all the Isshinryu masters long ago. Too many now to count.
My perspective is based on there being only one Soke (equivalent to "grand master" and is the proper title) when I started, and that was Isshinryu's founder, Tatsuo Shimabuku, himself. (Yeah, I'm old, having started in the mid 60's.) After he died, his son, Kichiro, assumed the role, and soon after, Tatsuo's son-in-law, Angi Uezu was acclaimed by many as a/the Master of Isshinryu. After that, the dam burst and there began a flood of masters here in the USA. Currently, I claim Angi's (and I use his first name with the utmost of respect) protoge, Tsuyoshi Uechi, as my master and his senior student as my sensei.
There have been, and are, some great American Isshinryu sensei who are called soke or grand master by their students and have earned their loyalty and respect. But the main thing in my book is to retain the teachings and principles of the original intent of Okinawan karate and not pay much attention to who calls himself a "Grand Master." I think my lineage allows me to do that.