I think that people should get married as many times as they want, and this includes Charlie Sheen. Although many people judge others when a marriage doesn't work out, especially if it happens more than once, I think it takes some people time to find the right person. Charlie Sheen could be like this.
Charlie Sheen is known to be a volatile personality. No woman in her right mind would marry the man, unless she were trying to take advantage of him. In that case, Mr. Sheen should not marry her himself, out of fear that she would take what remains of his money.
Charlie Sheen should not get married again. He seems to prefer the single life but if he wishes to get married then he should do what he wants. Most of his marriages that we have seen have not been so good for either party. I think if he settles down he would do alright.
Charlie Sheen is as funny as anything in his sit com, Two and a Half Men. But in his personal life he is a train wreck that has happened and is waiting to happen again. Without some intensive rehabilitation for drugs and alcohol and some self understanding, which is unlikely, he shouldn't marry again.
In the end, if Charlie Sheen wants to get married again and he can find a woman that agrees, of course he should be allowed to do so. However, given that the man has had so many problems in the past and he doesn't seem to care about the well being of his children, I believe it would be better for him to remain single.