Not quite there yet with my group but my interpretation is Yes. In the bestiary entry, Split is listed as a defensive ability and the slashing/piercing damage is listed as an immunity. It's a bit legalese parsing but the Split ability seems a reaction to the damage type instead of explicitly defining the immunity. If that makes any sense...
Of course my other interpretation is these are not really Ochre Jellies (living protoplasm) but rather animated magical fluid that behaves like an ooze. So you can do just about whatever you want. You could give them DR 10/blunt if you wanted or ignore it altogether.
And if you think that's a cop out - try this: you should do whatever you think will gross out, challenge or otherwise make more fun for your group. It's not like the RotRL police will be hunting you down for not doing it "right."
Hi everyone, I know this a bit late, but I have a question on this encounter too.
It seems to me that the jellies only have a +7 to hit which, against a lv 14-15 party, won't do much (Even the mage has 20 to AC), so I wonder how these things could even have a chance to inflict their effects, maybe I should treat their attacks as Touch attacks? But that maybe would be too much against the players.
How did you handle this? Did you use these jellies just to be annoying even if they have no impact?