Yer not suppose to use your own "new"

That's an overstatement.

No errors, however, the object returned is still a hash ref

Sure, because you told Moose to use its own new instead of yours.

package Module;
use Mouse;
sub new { return undef }
__PACKAGE__->meta->make_immutable( inline_constructor => 0 );
print __PACKAGE__->new();
[download]

I think it used to warn when new existed and you inlined the constructor. It really should. (Upd: OH! Moose does warn, it's Mouse that doesn't. Mouse-- lamprecht++ )