the duodenal switch is sometimes done as two surgeries, so that's not too unusual. Odd he wants to wait five years between them, though.
as far as losing weight, some surgeons have a BMI limit (for example, they won't operate on people with a BMI over 60 - or over 70 - or whatever). On someone with a really high BMI, the surgery is riskier, and some surgeons don't want to take the risk. So you'll either have to lose the weight, or find a surgeon who operates on people with high BMI's.