I guess that's true to an extent, but the way I would formulate that rule would be that most subjective qualities come before the noun (which is a more general rule that what you said), and more objective and descriptive adjectives come after. So here, you would probably say "Le grand vieil homme français" (The tall old man French).
That being said, it's not really a rule. In fact, the example still sounds somewhat uncomfortable to me, because "grand" and "homme" actually are kind of an exception. It's ok here because there's another adjective between them, but "grand homme" definitely doesn't mean the same thing as "homme grand". The first one means "great man", the second one means "tall man". You might say that this goes pretty well with the general rule, except it doesn't work with, say, woman. "grande femme" or "femme grande" mean the same thing. I mean, you could use "grande femme" in a context where you obviously want to mean "great" by mirroring the masculin idiom, but you would need some context for it to be understood in that way.
I guess, going back to the example, that you could argue that "tall" falls into the objective half, but "Le vieil homme grand français" or "Le vieil homme français grand" both sound wrong. You might say "Le vieil homme français, qui est grand" (i.e. "The old French man, who is tall"), but that's a big long-winded.
Basically : there is a guideline, but as always in French, half of the cases you'll find yourself in might be arcane exceptions to the rule.
Which puts French in a similar position to that of English I think. Mostly, some orders sound "right" or "wrong", and it's gonna be hard to tell them apart if you're just learning the language.
