You guys (even Mike) have this ALL WRONG!
This was obviously a confused and inexperienced umpire. When confronted by the defense, he is even more confused and looking for the easy way out.
Here is the result:
Umpire rules after-the-fact that it was, indeed, a strike three on B2 and B2 is out.
"Yes, coach (to the offense), I called it a strike. You can't argue balls and strikes."
The count is 0-1 on B3. Call B3 back to the box to continue her at bat.
Simple.
You guys are obviously too experienced to see the real-world solution to this!