hmm I just assumed they were active adapters...do they not make adapter mini DP to HDMI?
I've never seen an active one (not that means anything), and AMD doesn't even have a category for them. Http://support.amd.com/us/eyefinity/Pages/eyefinity-dongles.aspx
The stuff that comes with cards is usually passive, so if it doesn't work I tend to assume it's passive anyway since that's the first thing people try.
if he needs hdmi he can slap a DVI to hdmi adapter on a active DVI dongle.