been down this road before, what happens is the other company either lays down and dies on the subject or attacks, chances are they attack and it just ends up in lawyers making money, the worst case is the other company doesn't know until your mate spends all his money in development and THEN they attack which means he has to close down and loose what he's put in.
IF he has a good selling proposition then he doesn't need to go up against a trademarked name, most people who do this do not have a winning edge thus why they are trying to score off the established business.
he's heading for headaches and $$$$$$$$$$$$
tim
PS: if you want to PM me i could do some stealth research for you as one of my businesses is in the optometrist industry so i have contacts i can phone who tell me whatever i want to know. i'm www.optometristwebsites.com.au to be above board.