Walker took some advantage of ObamaCare and other subsidies to get people off of Medicaid and into private coverage: http://www.maciverinstitute.com/research/2014/10/report-medicaid-expansion---wisconsin-got-it-right/ This is in contrast to most other states which simply expanded Medicaid which is the worst case for both taxpayers and the recipients. In short he chose among various bad alternatives and did what was best for his state.
He had no choice considering the Dems did everything they could to squelch the alternatives like charity care, expanded HSA's, limited plans (e.g. without birth control and other nonsense), etc.