If your friend is using a proxy, all the requests will look as requests towards the IP of the proxy. Depending on your friend's parents' knowledge of networks, they might find that as a suspicious behavior. In normal cases where the average parents don't know much about proxies, there should not be any problem.
... and then redirect user to real site.
The characteristics of an MITM attack is that the attacker is in the path (in the "middle") of the traffic between client and intended server and modifies the traffic there.
Since the client is already trying to access the intended server a redirect will not be possible: one cannot issue a redirect to the ...