Kale has "High vit. A (89 IU/g), mod. oxalates, goitrogens" marked as use occasionally.
Similarly Buk Choi has "High vit. C, high vit. A (30 IU/g), goitrogens" and is marked use occasionally.
Mustard greens has "High vit. C (7%), high vit. A (53 IU/g), moderate oxalates (1287 ppm), goitrogens" marked as good for staple.
Turnip greens has "High vit. C (6%), high vit. A (76 IU/g), mod. oxalates" marked as good for stable.
I've been using buk choi as a staple for years , and have used kale too.
I think people who say don't use these are basing their opinion on the fact that the "beautifulbeardies" list marks them as use occasionally for reasons known only to the publishers as wrt vitA , and vitC and goitrogens they seem similar to the recommended greens staples.