It seems that both is true. And also, what about the electric trap in Going Up......? Does it appear somewhere else?
As for tseug's question, it's a blocker, and IIRC, the level is called 'Everyone turn left!' somewhere is the Present set.
Which DOS ONML Tame level is, without use of possible not-yet-known glitches, solvable, but not 100%-able with only one type of skills?