The measure allows the president to place troops anywhere he determines ISIS is operating. Therefore, it could be used to justify using military force against United States citizens on US territory. It may even be used to justify imposing martial law in America.
The President does not have to deploy the US military to turn America into a militarized police state, however. He can use his unlimited authority to expand programs that turn local police forces into adjuncts of the US military, and send them increasing amounts of military equipment. Using the threat of ISIS to justify increased police militarization will be enthusiastically supported by police unions, local officials, and, of course, politically-powerful defense contractors. The only opposition will come from citizens whose rights have been violated by a militarized police force that views the people as the enemy.