Currently the Robo Miner will not mine through open Mechanized Airlocks. In contrary Auto Sweepers will sweep through them if openend. Allthough this is consistent with the range indication when building the Miner it is inconsistent with the rest of the game mechanics.
Steps to Reproduce
Build a Robo Miner next to a Mechanized Airlock. In my case I used automation. When it opens it will not mine through it.
This issue has not been confirmed by a developer yet.