Failing to repay a federal student loan can knock you out of a bunch of stuff. For example, I could lose my Texas real estate license for defaulting on a student loan.
Something doesn't sound right about the scenario you are explain. I had two loans that were consolidated and I've never had problem getting a forebearance or deferral on my loan. You or he may want to investigate the situation more and see what options may be available.
I know my brother had problems with his student loan when he graduated from law school in the early 1980's. I think his problem arose because of having several loans which were unconsolidated.
The best way to tell if you can buy a house is to talk with a mortgage lender.