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


I’m having a dedicated in wall AC cable run, about 40-50 ft. I was planning on using VH audio cryo’d 10-2 Romex but the contractor wants to use BX since it’s an urban area and more impervious to mice, etc.

Any thoughts on this?

Also I was planning on wiring the end of the run with an 20 Amp IEC connector so I could plug it directly into my Niagara 7000. I don’t know if they will wire it this way but I thought I could always do that myself later.
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Reason million and one to not live in one of those God forsaken over regulated over taxed places.
Considering that pretty much every state has as law the National Electrical Code, what place where laws don’t matter do you live?  Cities often take these things more seriously because fires don't just take out one house, they can take out a whole bunch.
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.