That sort of exposure was not a valid reason to test for anything, certainly not syphilis. If there wasn't an obvious, fresh, bleeding cut in the skin at the site the blood contacted, then no any infection of any kind was possible. In theory syphilis might be transmitted by blood transfusion, but in fact such transmission has never been proved.
No ongoing discussion or 'yes but' or 'what if' questions for this sort of anxiety-driven question.
HHH, MD
It was a woman about 55 and was married for a long time.