I think if you mute someone in steemit, it has nothing to do with transfer of steem/sbd, as the purpose of "mute" in steemit is something else. You can transfer steem/sbd to a muted user also.
Purpose of Mute option in steemit
Mute Button allows a user to stop seeing the comments/posts of a particular user after having successfully muted them.
This function comes in handy when you are dealing with spam, or when you encounter inappropriate content/behavior that you no longer wish to see or experience.
Yes, it is. I just tried, and it's definitely possible, and not even a warning against it. And people whom you muted can also still send you STEEM, so it's no point in muting people who do transaction spam.