In isolation, this is fine but if this is a harbinger of things to come, it seems quite problematic. Tobacco use is extremely strongly correlated with schizophrenia and while this would be difficult to ascertain, likely schizotypy spectrum (most of whom would be undiagnosed) as well. This may not be an ADA violation per se, but it seems to have that type of effect.

Source: https://en.wikipedia.org/wiki/Schizophrenia_and_tobacco_smok...

Edit: Wouldn't this potentially fall under disparate impact?