Wowhead seems to be mistaken about:

I can accept the quest without having gone near the other 2 quests.

Grail-Quests-_classic_/Grail-Quests-_classic_.lua:G[2379]='L1052927 CR A:3401 T:3402 P:2378,2380 E31727

I suspect 2378 and 2380 are lead in quests and not actual prerequisites.

2378 and 2379 are mutually exclusive breadcrumbs to 2379. Obviously they are rogue specific. I did not determine if they were racially different.

Grail has been updated for next release to make them prerequisites.