I'd add to Craig's comment that you could modify the Scan/List panel to force an element selection list, but you could also easily add a validation using a Rexx snippet in panel rexx to disallow '*' anywhere in the Element/System/SubSystem fields but perhaps even easier to disallow ONLY an asterisk. i.e. AB* is ok (and for you '%*') but a simple if (&field='*') .msg = ... would stop the most heinous examples. Of course that won't catch folks who build/submit their own SCL, that would probably require an Exit.
However, If you haven't already I'd suggest you check out the ideation here A better Search Tool. If you want to give it a go, it's included in the LongName FDP prototype here: LongNameFDP