...while continuing to lay at a "false" price. I think it is underhand.
Twice I've been caught on this. Today in Hereford 1450, they continued to offer "4/1" about Manjam for about 45 minutes after a non-runner 10p rule 4 was clearly known to them, which they then happily slap on to the bet later without any indication at the time it was placed that price would be reduced.