Because those rules are in place for reasons. And some of those reasons are to prevent drug companies from turning the poor into lab rats with no regard to their safety. And I guarantee you, you let "terminal" patients skirt rules, there will be a hell of a lot more "terminal" patients.
And I'm sure there are some non-regulation reasons to limit various therapies. They are trying to see if thing X can help. And if thing X only helps when combined with thing Y, you don't exactly get that information when focusing on thing X. Or the worse scenarios of thing Y making thing X ineffective or harmful.
This was written from a very emotional place, and understandably so. But that state means they are not exactly in a position to consider all the reasons. And it must be frustrating as hell to have tried 40 things that didn't work to only be denied the 41st because you tried too many other things. Especially if that 41st thing turns out to be something that works.
But I don't think the answer is let terminal patients take whatever they feel like.