I would assume that most of the users of Daz Products are on Apple computers.
I think you will find that this is not a safe assumption. True quite a high proportion of Bryce users will be using Macs, as Bryce was originally a Mac only app, as we all know.
However you have to remember that traditionally the main Daz3D customer base were poser users and more used PCs than Macs. Those people who have moved over to Daz Studio will also be more biased towards the PC users rather than the Mac users, numbers wise.
Daz3D does have Mac developers, but the Mac developer who had the specialised Bryce knowledge was employed on contract, and the contract ended not long after the last Bryce dev cycle did. Lion did not come out until after the dev cycle for Bryce had ended.
Daz3D has said that when Bryce re-enters the dev cycle then they will work on getting it to work in Lion, and Mountain Lion, but haven’t given a time frame.
At the moment development is concentrating on DS and Carrara.