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.