So a needle has to be wasted, a sterile line and storage bag must be wasted, a professional's time must be wasted, and the potential bio-hazard material must be disposed of properly, costing the Red Cross even more.... all so some idiot (who CARES what his preferences or circumstances!) can feel good about himself, while knowing full well that his "sacrifice" is worthless, unwanted, and wasteful. Just frickin' great.
The moron knows that this will waste resources that would otherwise go towards helping save lives, but his fffffffffeelings *spit* about his "sacrifice" are far more important. What a great guy.
The reason they do it this way is so that when offices etc. holds blood drives no one has to know that you are (for whatever reason) ineligible to give blood. Many companies put a lot of pressure on their employees and this gives those that really shouldn't be giving blood an "out" so that they can appear to give blood but don't really.