Who cares? This law, useless as it may be, will make us FEEEEEEEEL better! And it will let tax-and-spend leftists appear "tough on crime" to appear to moderates! Waah!
Once it is proven that the mark can be removed easily, they will pass a law making it illegal to remove and another law requiring that gunowners submit their guns to annual testing and another making it illegal to change any part of your gun without submitting it for testing. Don't worry, there is only a 11 month backlog for testing.