Though everyone has the right to refuse the AIT machines, this kind of stance is important to be published.
Without it, you're much more on your own by consistently refusing and encouraging/education your fellow crewmembers to do the same. You may end up getting yourself labeled as a problem child, which is never good. With this kind of backing, you are much more likely to find your coworkers doing the same and its no longer you sticking out, its you following the guidance of your union.
This may not be important at many airlines, but at some airlines with very heavy handed / threatening management practices, it could make a world of difference. This is why we need this sort of statement from ALPA.
Secondarily, having major organizations advising their members to refuse may have potential to push for having a flight crew exemption, expansion of crewpass, etc. It could benefit us all.