Performance of Viterbi detector over non-minimum phase channels
The Viterbi algorithm for optimum detection in the presence of intersymbol interference (ISI) is always preceded by a whitened matched filter (cf. this article by G.D. Forney). So if you use - as mentioned in a comment - the equivalent discrete-time channel, which then also includes the whitened matched filter (WMF), then, due to the properties of the WMF, this model must always be causal and minimum-phase. So, regardless of the actual impulse response of the channel, the complete equivalent discrete-time model (including the WMF) can never be non-causal or non-minimum-phase if implemented correctly.