Yes, the improved code is fine, and covers all cases.
However, the goal is to have code which is fine and covers all cases AND IS SIMPLER. I want simple because I need to recommend this to testers who don't know necessarily know what a regular expression is. I can tell them to stick in a \b at the beginning and end of each word to be matched, and I can even explain it to them. Unfortunately, \b doesn't always work.
The more complicated expressions such as you used (and I suggested) are not so easy to recommend or explain. I just want to know if there is some simple way to do what seems like a simple task.