The first thing to do is wait and see.
He has a job, he has been paid and the employer can redeploy him I would have thought at will. Hence he has no loss and so no come back.
BUT
a little later, he could ask for written confirmation that he has been exonerated - he missed a chance to ask for that at his reinstatement meeting.
and the other thing is: he can lawfully ask for any documents with his name on ( as they are his data) that relates to the episode under the Data Protection Act.
but you know, he may want his job ( until he gets another one ) in which case just carry on and keep your head down.
How do you know the accusation was malicious ?
and at his reinstatement interview, did they say they were unfounded AND malciious ? It may be worth getting a letter if they did