Why do you think it needs to be executed with 'this'.
By the looks of the script you can execute it with just:
[] exec "bib_militia.sqs"
and it whould work fine.
Note that when you're creating units, you must have already defined a group, which you use in the createunit command. You have the group as East1, where you're creating the units into.
If you don't have the groupname defined, you can do this by inserting a unit in editor and typing in his init field:
East1 = group this; deletevehicle this
Doing this will add the East1 as a name of a group in the mission, and then delete the temporary unit.