there isn't a sufficient number of Efika end-users who might be interested in MorphOS to make it worth to fine-tune MorphOS for this board

It is true, but there is a feedback loop. If there is MorphOS for Efika, Efika may get more users because of this. In my opinion releasing MorphOS for Efika with PowerUp rules (no user support, "use it at your own risk") first, can increase number of users and make the finetuning worth the effort. Some users may even help with finding and fixing problems.

I think the problem is located elsewhere. Efika is on sale already and it is sold by Genesi. Releasing MOS for it officially (even not supported version) will create some added value for Efika and I guess MOS Team and Genesi do not have an agreement yet how this added value should turn into real money for MOS Team. It is understandable that MOS Team will not release Efika MOS just for free and only increasing Genesi incomes.