Actually Tami, if you get an Intel Mac (which is actually just a PC with a different operating system), SRB2 should run properly on it - or at least it will soon. Do we have an Intel Mac port yet? It should be easy to do and everything should work properly...
SRB2 *does* run very well on Linux. The problem with the MacOS is that it's proprietary, just like Windows, so it's hard to people to build projects for it - AND the documentation for making software isn't as good as Windows. So you end up with a) difficulty creating software, b) great expense creating software for the machine, since the machines cost twice as much, and c) small user base. So it's not any disgust for the Mac platform, it's just very hard to support such a costly platform with so few users.
That being said, if you want to see a good Mac port - buy Alam a Macintosh!