UPDATE 3:50pm: OK, it sounds like you can completely disregard all the Medicaid-related stuff below; apparently there was a communication error. I've confirmed with the Whitmer campaign that the proposed reinsurance plan would not be tied in with Michigan's ACA Medicaid expansion program at all, nor would it have any impact on the Medicaid eligigibility threshold, which means this would indeed be a standard ACA individual market reinsurance program after all...which is what I assumed in the first place, and which would be perfectly fine!
Later I noted that his primary opponent, former State Senator and County Prosecutor Gretchen Whitmer, has far thinner responses posted on her website when it comes to healthcare policy. I also noted that there are some good reasons for this which likely have nothing to do with being "a tool of the insurance lobby", a "neoliberal sellout" bla bla bla and so forth.
However, for the record, yes, Ms. Whitmer does indeed support universal healthcare coverage, as shown in the Q&A video clip above from one of her town hall appearances (thanks to Mary Bernadette Minnick Weatherly for the clip and the OK to repost it).
Below is a verbatim transcript of the whole exchange: