Yes, Dr. Friedman was asked to analyze Sanders' health plan.  Considering the size and scope of our health care system, the degree to which one gets into the details of analysis is a highly relative question.  Furthermore, your anecdote about his belief regarding details is misleading in this context. His analysis of Sanders' ECONOMIC proposals is reported in an academic paper, complete with all the details he used in his analysis. 
Dr. Friedman uses the same macro economic models that Krugman has advocated for years., the only places he could have introduced bias were in the multiplier factors associated with various activities. According to several economists who have spoken up on this issue, AND who have actually done a critical review of Dr. Friedman's analysis, the multiplier values he uses are quite reasonable and defensible, being within standard ranges.
And regardless of your guilt-by-association insinuation, Friedman had previously donated to the Clinton campaign, not Sanders.