I don't think you'd be going against BRL's wishes by uploading the ported source code. I think the only real restriction with the betas, other than obvious copyright/piracy infringments, was that you weren't allowed to distribute any executables created with the beta's.
Given that BMax has been formally released on the Mac, and that BMax source code is supposed to be the same for all three versions, the source code you have created by porting the NeHe tutorials is effectively valid Mac BMax source and thus should be allowed to be distributed.
But regardless, you do what you feel is right. I am greatful to you for porting these tutorials, and I'm certain once they're posted on NeHe, a whole lot of other people will be too.
Given that BMax has been formally released on the Mac, and that BMax source code is supposed to be the same for all three versions, the source code you have created by porting the NeHe tutorials is effectively valid Mac BMax source and thus should be allowed to be distributed.
But regardless, you do what you feel is right. I am greatful to you for porting these tutorials, and I'm certain once they're posted on NeHe, a whole lot of other people will be too.