You mechanic friend is a fool or you misunderstood him. The MC cap has an air hole in it.

One man bleeding can be tricky.

 

If your old fluid was at all suspect, you will need to cycle the ABS, too. I used to do mine myself on another car after driving events. With speed bleeders and some time, one person can do it. I pushed a bunch of fluid out, cycled the ABS (by hard braking), and then repeated the flush at least once more. The reason behind this is that there is old fluid (or air) in the lines going to/from the ABS module. A dealer can get it clear, but shade-tree guys have to cycle the ABS.