Posting three responses with substantially the same information is not helpful to the OP and just makes extra work for the Moderators.
Whilst I won't argue with the principle of a companion answering on behalf of the claimant, there is a fine line to be drawn in doing this, first of all it is at the discretion of the assessor and if they are not happy with the interruptions by the companion they can terminate the assessment on the basis of the claimant failing to participate.
To be clear there is no exemption from a face to face because the claimant has Autism.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems