The exception is no longer thrown, and so the immediate problem is solved.
However, the way it is constructed now, even a valid URI parameter configLocation is effectively ignored if the default configuration fails (i.e. returns the SimpleLoggerContext). This leaves no possibility for configuration in this case, significantly reducing the features of Log4j2.
Should this be stated as a new bug or continued in this issue?
Btw: If I see it correctly, the SimpleLogger can never be used as a normal Logger for Log4j2, but only in the context of the StatusLogger. This may be the intended behaviour; if this is so, however, the class comment in SimpleLogger.java should be altered accordingly.