That is a false choice. If Kanter gets 75 minutes from Williams, he has the third most minutes on the team, behind only Hayward and Burke (2213)
If Kanter had not started the season injured, he would have had those 75 minutes easily.
However, it is extremely silly to think an additional 75 minutes, tacked onto the 2100+ minutes he already played, is the difference between developing Kanter and not developing Kanter. Giving him minutes just to boost him on the minutes chart makes no sense at all.