Ooooopsss!

I've just caught wind of an unfortunate occurrence at the 2017 World Seniors. In the game between GM Rogelio Antonio and IM Alexander Reprintsev, the following miniature occurred. 1.e4 d5 2.exd Qxd5 3.Nc3 Qb5?? 1-0
In moving the queen to a5, Reprintsev placed it on b5 instead (or at least enough of it to matter), at which point it was able to be captured by bishop or knight (One report indeed had 4.Bxb5+ as being played, although this didn't appear in the online version I saw).
There is some argument that Antonio should have let the queen go to a5 as intended, and if I was White in these circumstances, I would have done so. On the other hand, if I was Black, I would have let the move stand, accepting the responsibility for my mistake. And finally, if I was an arbiter, I would almost certainly let the players sort it out among themselves (ie if neither player claimed a breach of the rules, I wouldn't go jumping in)