This video is pretty good at pointing out that Creationists with PhDs are essentially for show. Using Dr. Russell Humphreys as an example, he shows that the journal/paper writing and citation frequency is far below other scientists, and so such people don’t advance science in any meaningful way, and the application of their PhDs is very limited indeed.
I would like to see more generalised and average figures for scientists, rather than the few examples shown, and some analysis of Creationists in general (as it ends up being anecdotal, mostly due to the reason of the video being made being about Humphreys in particular). But the general idea seems to be bang on. The PhD advertising of such people is more about credibility for the Creationist organisations than for any meaningful reason.