Steve lets it go. He sure as Hell can't explain any of it. He barely understands how Vision was born in the first place. The allusion Tony is making is within his power though.

"Natasha can take Wanda out while you visit." He offers even if it isn't much. The guilt on his face makes it clear he doesn't like this option at all. It feels too much like enabling a bad situation. "But, if you really don't want to come then fine. I understand."