Well, after searching through the FAQ on the BOH site and generally looking everywhere else on the site, I am not convinced that you are being completely honest (with us, and perhaps not even with yourself) about your reasons for NOT supporting MorphOS2.x,
I can guarantee I'm being honest and I hope I'll manage to prove it with my replies

or allowing anyone else to collaborate with you and support such a port for you (It could be done with no required time or effort on your part)
I'll explain better the two reasons I gave in my previous post:
1. I don't want to give away my code (call me stupid, if you want, but I'm extremely jealous of what I produced with so much love, and that goes beyond BOH's code, as much more stuff is involved);
2. a collaboration would require time and effort on my part: initially, I would have to provide the stuff, to explain how to setup the system to get the code to compile, to collaborate to tackle any problem that might arise, to prepare an update package that allows installing the game on MorphOS from CD-ROM (just like I did for MacOS, Linux and AROS), to update the ISO image, to prepare a new demo, to make sure everything works fine; then, in case of future updates, practically the same effort would have to be done to produce the new version and update package; finally, supporting MorphOS users would be more complicated and time/energy-consuming.
NOTES: reason #1 alone is a show-stopper; collaboration might be much more taxing than one could ever imagine - just to give you an idea, collaborating to the various translations (only a bunch of mostly simple strings) required many hours of work.
It would seem to me that MorphOS2.x running on any G4 Mac w/800MHz or faster, could probably run BOH with no problem
MorphOS machines are certainly capable of running BOH - I never said the opposite.
and there are several MorphOS developers that have already completed many ports of SDL games & applications to MorphOS2.x. I am quite sure at least one of them would be willing to support a port of your game, either officially, or unofficially released by you.
Sure. As I said in my previous post, I did receive collaboration proposals.
Your quote that the "price is just unbearable" to support a MorphOS2.x port sounds a bit dramatic and leads me to think that there is perhaps some unstated element of your not wanting to support MorphOS2.x, or allow anyone else to port it. I will give you the benefit of "doubt", but it is very disappointing that you have chosen to exclude MorphOS2.x users for any reason. 
The price is that the amount of headaches is huge with respect to:
a) the time/energies I can dedicate to the game (having to support one more platform, on top of other 5, plus 2 alternative distribution channels which take also extra effort because they handle the stuff according to their own framework, is a burden per se, not to mention that not having direct access to the platform complicates things quite a lot);
b) the size of the MorphOS community, which not big enough to justify the port and its management from a commercial point of view.*
*Just to be clear, I'm not implying that the situation with AmigaOS and AROS communities is any better, but: the AmigaOS version exists because I "live" on AmigaOS, so it was natural to develop on it and for it; the AROS version exists precisely because I gave in to the temptation of making the port for AROS (which looked so tempting, given that it's easily accessible) and make a larger part of the Amiga community happy - although, I have to admit, I (almost) regret that choice because the effort has not been repaid (but, of course, I'm very grateful to those AROS users who bought the game and, just as obviously, I hold no grudge against anyone who didn't).
Finally, some food for thought...
I've been asked to port the game to several platforms (OpenKODE, GP2X, classic Amiga, Natami, C64, Nintendo DS, PSP, XBox, PS3, iPhone/iPod/iPad and maybe others): some are just not suitable, but others not only are suitable, but also offer better/good commercial perspectives. As you can imagine, if I could afford to make more ports, I'd consider the "promising" platforms... but the situation now is that I just can't do more.
The bottom line is that all I can say to MorphOS users is: sorry, it would be nice, but I can't, and I hope you understand.