The Binary syntax from RFC 2252 (which was removed from RFC 4517) is documented in our schema reference as:
Values of this syntax hold binary values.
The values are BER-encoded instances of an attribute value ASN.1 data type for X.500, where the first byte inside the OCTET STRING wrapper is a tag octet, and the OCTET STRING is encoded in primitive form.
To my mind, this means it should be used with the LDAPv3 ";binary" transfer encoding. However it is not - the server allows/disallows the use of ";binary" according to the syntax implementation's isBerEncodingRequired() method, which BinarySyntaxImpl inherits from AbstractSyntaxImpl, which returns false.
I think BinarySyntaxImpl should override this method and return true.