Why can't I use a Robot Workbench at Boston Airport Ruins?

Solution 1:

This is embarrassing, but I figured out that it was simply because I was in power armor.

For whatever reason, I was experiencing a bug that made this less obvious than it should have been. The little messages that pop up in the top left? They weren't showing. When something was added to my inventory, for example? Nothing! And the same here. Normally, I would have seen a message, "You can't do that while in Power Armor."

I confirmed that I can craft at this location when not in Power Armor. In fact, I created an absolutely lethal assaultron/robobrain hybrid named Deathsheba, and she is awesome.