Yeah, as some now famous NY Senator once said, "It's a vast right wing conspiracy".
Seriously though, in my judgment this whole issue is basic cost/benefit analysis. Cost/benefit analysis is a relatively simple and widely used technique for deciding whether to make a change. As its name suggests, to use the technique simply add up the value of the benefits of a course of action, and subtract the costs associated with it.
In this instance what are the value of the benefits of replacing a bad AIR pump? Negligible in my estimation. You get a "proper" running MB again. This is obviously worth more to some than others. You don't need it to pass a smog check as repeatedly stated in this thread, but
you might be caught with it disconnected by the inspector as others have mentioned, but the chances of this happening are scant, and if you're worried about this, well, just hook the dang thing back up again after it's warm and drive to your smog check. Environmental benefits? Slim to none -- but again some people may place more importance than others in this area.
Costs of replacing the AIR pump? Too much! $1000 or so I've heard for a new one.... $400-$500 for a rebuilt unit.
IMO the costs clearly outweight the benefit ... and disconnecting a bad air pump is the way to go.
To each his own.
Happy Holidays,