Though alcohol is far more dangerous than cannabis, alcohol gets a free pass because the federal government, which the NRA purports to mistrust, does not violently punish people for using it. The NRA remains silent when that same federal government, which, again, it believes its constituents might need to overthrow at some point, violates the 2nd Amendment. Rather than questioning laws as the glorified 18th-century American rebels did, the NRA prefers the government they mistrust simply enforce existing gun laws, like denying cannabis users their rights.
Apparently, the organization only believes in the notion of "shall not be infringed" if gun owners align with their own right-wing establishment views and law-and-order agenda, which often command submission to the very government they fantasize about overthrowing.
Read on:
https://www.lewrockwell.com/2017/12/no_author/nra-silent-as-states-feds-ban-gun-sales-to-medical-marijuana-patients/