Charlie Sheen played a very important role in the show 'Two and a Half Men'. While his being dropped from the show was certainly understandable due to his personal problems and bad behavior, enough time has elapsed to allow for Charlie Sheen to reprise his role one last time during the series finale. Fans of the show would overwhelmingly support seeing him back one last time, and it should not be too difficult to accommodate Charlie Sheen for one last show.
Although Charlie Sheen was 'kick off' of Two and a Half Men, none of us know what really happened. What we do know is the show is wildly successful and Charlie Sheen has become even more famous. Welcoming Charlie Sheen back for the finale will help ratings even further, which is exactly what the network wants.
Charlie Sheen, despite his misbehavior, was a huge part of the success of "Two and a Half Men" during the show's highest points. CBS should welcome back Sheen for a portion of the finale, at least in a dream sequence or a flashback. Having Sheen on the screen one final time in that show would be appropriate, even if it is just for 10 seconds.
Charlie Sheen should not be welcome back on Two and a Half Men because Sheen is not a good professional bet anymore. He has taken many unethical and illegal steps in his recent life, such as drug use and domestic violence, and this behavior shouldn't be rewarded for more financial gain and media attention.
I do not believe CBS should welcome back Charlie Sheen for the Two and Half Men finale. Sheen was removed from the show for specific purposes that had to do with his ability to act properly on set. Just because he would be showing up for one episode should not allow his return. I'm sure it can be complete without him.