I've blocked that UA for so long that it may be one of the five oldest specific-UA-blocks I've still got (I switched primarily to whitelisting UAs years ago).
Self-referring page requests are often a clue that it's a 'bot trying to be stealthy. I block such requests under certain circumstances.
But you have to be careful about blocking self-referrers if the referring page contains any "named anchors" because most user-agents (excepting Safari) will not send the URL-fragment used for named anchors.
So if for example you have a link like <a name="this-page's-URL-path#TOP">Back to Top</a> link on the page, then clicking this link can trigger a self-referred request on non-cacheable/short-expiry-time pages, if the visitor has browser caching disabled, if he/she flushes the browser cache after initially loading that page, or if he/she (somewhat erroneously) uses middle-click to open that link in a new tab (in MSIE), and you almost certainly don't want to block those requests.