There is no easy way that I can think of to detect the platoon leader, meaning it will be difficult to give only the platoon leader actions. Some solutions that I can think of right now
Give all roles with a manpack radio the actions
Make a new "platoon leader" attribute for the roles configuration
Add a list of names that the platoon leader role could be (e.g, "Platoon Leader", "Platoon Lead", "Plt Lead", etc.) and check them with insensitive case
There is no easy way that I can think of to detect the platoon leader, meaning it will be difficult to give only the platoon leader actions. Some solutions that I can think of right now