With referee Chris Foy having awarded a free-kick at the time of the incident, the Football Association considers the matter to have been dealt with.
Platt said: "I wasn't surprised, based on the rules the FA has put in place if the officials have seen it.
"There have been precedents set, and not only have precedents been set, they've actually gone on record and said if that's the case - I wasn't surprised.
"The rules are the rules. We don't make them up, we adhere by them."
Platt has dismissed a suggestion that luck has evened itself out.
He said: "I don't know if it's luck and whether we've had it. What is luck? I am not sure.
"It is a situation that has gone. I am not surprised he has got off. They are the rules, the officials saw it."