No, he does not have to file an IN tax return.
Indiana and Wisconsin have a reciprocal tax agreement. This means his IN earnings are only subject to WI tax and he doesn't have to file a IN tax return (unless his employer withheld IN tax)
A reciprocal agreement, also called reciprocity, is an agreement between two states that allows residents of one state to request exemption from tax withholding in the other (reciprocal) state. This can save you the trouble of having to file multiple state returns.
For additional information, see What is a state reciprocal agreement? and Which states have reciprocal agreements?
