The rationale in the US law is that the crime is an equal moral failing to murder. That may be irrational to you and I, but that is the law.
Just as being an accessory to murder would be considered "very bad" so too would supporting cannabis use in any way. According to US law he is investing in a criminal enterprise, similar to funding a cartel in Mexico. The law doesn't match the common person's perception of severity, but the US border guards will enforce the law as written.
Again, none of this prevents you from merely learning about cannabis. It requires action of some sort to further the use of it.
Just as being an accessory to murder would be considered "very bad" so too would supporting cannabis use in any way. According to US law he is investing in a criminal enterprise, similar to funding a cartel in Mexico. The law doesn't match the common person's perception of severity, but the US border guards will enforce the law as written.
Again, none of this prevents you from merely learning about cannabis. It requires action of some sort to further the use of it.