You are right, I mainly presented this as an easy hack of getting 90% there. Even with the examples you give, if I have my own dictionary, or generate a special one ahead of time, this procedure will work fairly well. For example I can generate abbreviations, without too much effort, from an existing dictionary which will cover your PLNE example. (L33T requires some work, but if you use it I pity you.) The dictionary your method uses is in a human's head. Sometimes these work well, sometimes they don't.

Re: MUFC -- I'll probably get downvoted/flamed for this, but I'm a reds fan. To some that is truly a 4-letter word. :-)