I think it's true. Captain America could have picked uo Thor's hammer - but I think he didn't do it for two reason. One reason is yours. Another one is - HE FELT NOT READY.
In one of the trailers we can see the same figurine that was on Agatha's wall, so maybe she wil be somehow important to the story of Wanda. I wrote more about it on my blog for Polish people, it's called Doktor Strange 2 CDA - things you've missed.