Hello and thank you for entrusting me to assist you. My name is ***** ***** I will do everything I can to answer your question.
Unfortunately, employment in the state of Illinois is "at will" absent an express agreement to the contrary. At will employment can be terminated for any reason not amounting to discrimination on the basis of a legally protected trait (race, religion, gender, etc.) or retaliation for engaging in certain forms of legally protected conduct (filing a wage claim, taking FMLA leave, etc.). It doesn't matter whether the basis for termination is fair, reasonable or even true.
What this means is that an employee who gives advance notice of their intent to quit has no special rights or protection. Their employer can respond by immediately terminating them, by demoting them, or by reducing their compensation. Again, this is because the terms of employment can be changed at any time except for reasons relating to legally protected traits or activities. Giving notice of a resignation is neither.
So, I'm afraid all someone in your husband's circumstance can do is attempt to reason with his employer or resign sooner than he had planned if the terms of employment are no longer acceptable to him. He would not, however, have any legal basis to sue given what you have described.
I hope that you find this information helpful and am genuinely sorry if it is not what you were hoping to hear. Please do not hesitate to let me know if you have any questions or concerns regarding the above and I will be more than happy to assist you further.
If you do not require any further assistance, please be so kind as to provide a positive rating of my service so that I may receive credit for assisting you. Very best wishes moving forward.