Hi there, I'm going to weigh in on this one. (Pun intended )

Last summer I bought my first bike in a decade or three. At the time I weighed approx 320lbs.

My suggestion would be to have your friend look at a recumbent with cruisers or comfort bikes as an alternative.

Reasons for a recumbent:
1. Easier on the knees and lower back.
2. Less weightbearing than a std upright bike.
3. Big comfortable seat. (My personal favorite!)
4. They're cool. Seriously weighing over 300lbs and having someone come up and ask about my cool bike was great.

Specifically I'll recommend the EZ-SC (super cruiser).

This is a design by the Easy Racer people(Easy Racers ) but it's an import by Sun and most LBS can order one. They are also pretty easy (and a bit cheaper $350 +/-) to buy on Ebay.

It has a low step over height.

It is a modified recumbent (i.e. the crank is below the seat height) which is, IMHO, more comfortable. The position is very close to many recumbent exercise bikes and actually your friend can try a recumbent exercise bike as a test.

It has little to no learning curve. Both I and my SO got on and road it without any problems.

If cost is a major issue or your friend simply doesn't like recumbents, hit a local sport store or dept store and look for a cruiser or comfort bike.

IMO I wouldn't worry too much about the weight rating. Why? Because in part, weight rating is based on use. Most likely your friend isn't going to be doing 30mi a day 3 times a week, or jumping off curbs, etc.

Sharky