MORE Act or cannabis removal from DEA schedule 1

The MORE Act will likely come up in Congress during the Biden administration. It seems to me that if cannabis is legalized on the federal level, then it would no longer be considered an “illegal drug” as far as the background check is concerned. In such a circumstance, do you predict guidelines would have to be changed to address this so that people are not denied for engaging in behaviour that used to be but is no longer, illegal?

Even if the MORE Act does not become law, President Biden could order the DEA to remove it from schedule 1 and it could end up on say schedule 2, 3, 4, or 5. For someone who holds a state-issued medical marijuana card with a prescription from a doctor, it seems to me that the user would no longer be using cannabis illegally any more than someone who takes any other prescribed controlled substance, such as alprazolam or hydrocodone. Given this scenario, am I correct in assuming the application cannot be denied for simply using a legally-prescribed drug? In fact, I cannot say for sure but it seems the Americans with Disabilities Act might even prohibit such discrimination.

My assumption is that if it were to be considered federally legalized people would still have to list it for several years. If it was used illegally prior to the date of legalization it’d likely still have to be listed.