In here a logfile-message is directly shown in the rendered part of the page, but it should be displayed as plain text as like as otherwere. Often the page content, starting with a deletion template, is part of the logged reason. Now in the middle of a Sytem message the template is expanded, which looks very odd.
So I propose to wrap the $2 into a <nowiki>. I'm not sure whether to do this to the system messages at translatewiki or implementing a php fix which does that automatically.