Dedicated AC line - Contractor wants to use BX instead of romex

Reason million and one to not live in one of those God forsaken over regulated over taxed places.

oh you mean the places where so many artists live, play, and create the music we listen to? They’re called cities and they’re the engine of a whole lot of culture and progress. I’ve lived in many of them and I love them. 

I live in one of those God forsaken red states and we're up to the most recent NEC.

Well... since I'm a licensed electrician and I'm guessing from your uninformed comments you are not congratulations on knowing the acronym NEC. Only commercial construction and over populated densely packed & infested cities require conduit.  Single family homes that make up 98.4% (I looked up the statistic just for you) of all domestic construction across America do not require soft or hard conduit.  An yes those places where culture and art are sooooo very important but no one actually does anything meaningful or make their own way... but just complain and hold their hand out for "their fair share" is exactly what I am talking about.  We the people means THE INDIVIDUAL not as BoBo says ie: the government.

Only commercial construction and over populated densely packed & infested cities require conduit.

Not in my red state. I was required to run through conduit in one of those areas populated by cows more than people. Single story ranch. You need to quit generalizing. If you are a licensed electrician you should know there are codes where conduit is required for certain applications. 

40 to 50 foot run of BX ,
In Chicago BX could only be used for short runs ( 6 -8 feet )  
the rest had to be conduit .
So to have your cake and eat it to ask your electrician 
if he'll run 3/4 inch greenfield ( flexible conduit )
 for you with your 10/2 romex inside 
with a ground wire or a dedicated grounding rod .