So by RAW it seems that even if they take the second option, only the creature with the gaze attack gains concealment. Silly and most DMs would probably rule otherwise but it seems like RAW.An opponent can avert his eyes from the creature’s face, looking at the creature’s body, watching its shadow, or tracking the creature in a reflective surface. Each round, the opponent has a 50% chance of not having to make a saving throw. The creature with the gaze attack gains concealment relative to the opponent. An opponent can shut his eyes, turn his back on the creature, or wear a blindfold. In these cases, the opponent does not need to make a saving throw. The creature with the gaze attack gains total concealment relative to the opponent.
Hm yes, I didn't think of that. I concede the point again.
Ah I see. I beleive the RAI was that the slime would only coat the pseudopods (due to it saying "A slime lord’s pseudopods are coated with slime that can paralyze a foe.") but of course RAI doesn't count for much.
For a RAW argument I would point out that it says "natural attack" not attacks. So by RAW only one of the natural attacks would gain the benefit of the slime. Since it doesn't say which natural attack gets the benefit of the slime the most sensible interpretation is too assume it only applies to the pseudopods (though you could make the argument that you get to choose).