I'd have to agree with the second poster - it should be an oversight.

We all know how WorldPerks and OnePass programs are different, but this is what Northwest offers from KLM:

Elite Qualifying Fare Classes:
Elite Qualifying Miles at 150%: P, F, J, C, Z, S, B
Elite Qualifying Miles at 100%: M, H, Q, V, L, T, K
Elite Qualifying Segments: P, F, J, C, Z, S, M, B

I'd also imagine that S accrues 150% on Continental. It's interesting to note, however, that at Continental, 'B' class only earns 100% EQM.

-RM