Good Question! (based on that scripture you quote)
I would say they are allowed to comment/give talks beacuse when they comment or act out a demo / talk they are technically not "teaching"...just commenting.
It's funny, cause usually the sisters are smarter than the bros. anyway. :-) I remember being so nervous condicting Bk study when I was an MS because several of the sisters comments were better than any conducting / "teaching" I could do!