No the flag cannot prevent your deployment forward.
Flags prevent favorable actions. Perhaps your chain of command is viewing the deployment forward as some type of favorable action in that you might receive special pay, combat patch, etc. However these are not favorable actions.
Your chain of command does have the right to determine who deploys forward based on their assessment of the situation and your skill set.
Items to Consider
Consider speaking with your platoon leadership. If that does not work consider seeking an audience with the unit commander on open door policy to ascertain the reason you are not being allowed to deploy forward, other than the flag.