[doublerabbit]

This was more Apple's doing rather than Valve's.

Valve wanted steam to co-exist on the mac in the early days and John Sculley of Apple didn't want Apple to be seen as a gaming device or a "personal home computer". So they ceased contact with Valve and the rest is history. https://www.youtube.com/watch?v=lPTLPXNtb2I

Apple refused to license joysticks so they could prevent customers from considering early mac's as game machines and deliberately refused to support games on the machine. Myst was only few that were exclusive to the Mac; that they then ported to PC.

[Wowfunhappy]

Your timeline doesn't make sense. Steam launched in 2003. Scully was forced out of Apple in 1993.

[doublerabbit]

So, your right. But the still holds true, that seed was what was sown not to encourage games for the Mac.

If you watch the YT video they go in to depth that they attempted to port the game and was axed by apple.