I don't think that's a Moo/Moose-compatibility issue (I could be wrong, and if so, would like additional clarification). It would be equally problematic with Moose, wouldn't it? At least after converting it to Moose by quoting the isa component, I get:
Cannot delegate my_array to elements because the value of maze_map is
+not an object (got 'ARRAY(0x163b880)') at...
...which seems to be the same type of error produced under Moo, with a slightly different message.
But I suppose I should be asking for clarification. Should that work under Moose?