I do not understand that too. I personal would have neither developed X5000 nor Tabor. It is a financial risky bet. On the other hand... not my money in fire
Except money invested in hardware development can generally be recouped or worst case, written off as a material loss.
On the other hand, software in this market always seems to require an extensive budget and protracted timetable, with new releases coinciding with leap years.
If OS support was delivered when the Tabor was announced it might have made sense - in October 2015.
We're now looking a period of up to 2 years for it to materialize. And that means more "stick with the PPC" mentality, long after the shelf life of that processor expired.