I'm a little confused on why I cannot apply adrenaline or adrenaline shot to a sniper.

Units cannot have the same type of buff applied twice, but they can have a similar buff and debuff (ex. firepower AND pacify ground).

The symbol on the sniper is of the debuff variety. Shouldn't I be able to buff my sniper if I would like to? I know this isn't in the "flavor" of the card, but I would like a rule clarification on when I can and cannot buff or debuff units.