I checked that, and also page 21.
And I rest my case: both pages show #L as "left speaker +". I do not see any ground wiring from #L.
So I guess your phrasing should be understood as "GND is wired directly from PSU to both speakers negative pin", which then would accurately describe the wiring diagram (please correct me if I am wrong).
As for Battletoads, no offence taken. I was just asking and you answered this question without ambiguity, which is exactly what I expected.
It is incomplete indeed and should be discarded.