Subclause 7.6.2.9 [expr.delete] paragraph 6 specifies:

... The destructor shall be accessible from the point where the delete-expression appears. ...

This check cannot be performed in case the operand of the delete-expression is a pointer to incomplete type.

Possible resolution:

Change in 7.6.2.9 [expr.delete] paragraph 6 as follows:

... The Unless the object being deleted has incomplete class type, the destructor shall be accessible from the point where the delete-expression appears. ...