The answer to your question in short is NO.
1) Chances of a pregnancy occurring during a period are practically nil
2) it takes penetrative, unprotected sex (the semen has to be deposited near the cervix which is located INSIDE the vaginal canal), for pregnancy to occur.
3) toughing and rubbing the vagina with WIPED hands would ensure no sperm enter the cervix. Even if he had some traces of semen on his hands, a pregnancy occurring this way would be a wonder, if not extremely rare.
Yes, a fifth of pregnancies occur because couples are irresponsible during mutual masturbation sessions.