I think you're confused. It's a weird turnaround, but in this situation the liberals and gun-haters are very much OPPOSED to incorporation. Just take a look at the
City of Chicago's brief if you don't believe me.
They're scared to death that their precious handgun ban won't survive incorporation, as they should be, since the gun ban didn't survive a 2A challenge in DC.
Excellent brief. It clearly states and cites the long unbroken string of legal precedents and it provides numerous historical facts regarding recognized state rights as demonstrated by actual municipal regulations going back to the earliest days of our nation.