I can’t help but to think this is much ado about nothing.
The EF has only been widely available since 2007. The Knights of Malta since the first Crusade. They celebrated the OF exclusively with no issue for many years.
I can see, just based on my personal experiences, where having both forms available might cause divisions in the organization. I would also imagine that those who are “attached” to the EF is a much smaller number than those who are not, so this just makes sense.
No one has a “right” to have the EF Mass and the Grand Master has every right to do what he sees fit to keep his organization ficused on what really matters.