The Met's probe was supervised by the Independent Police Complaints Commission, but Mr McIntyre asked: "Why are the police investigating themselves?
"Does that make sense to you, that the police attacked a man in a wheelchair and then they investigate themselves?"
He went on: "Throughout the report the police officers involved have stated that they were acting in my best interests, and this appears to have been accepted by those carrying out the investigation."
The force appeared to believe that "the fact someone has a disability renders them incapable of determining their own best interest or to act with autonomy", he said.
Following the investigation, internal guidelines will be drawn up on the most appropriate way to move a wheelchair user in such circumstances.
The Spanish Policia are thought to be helping with this process