He's already rested for 2 hours (= 8 hours, before SOMEBODY TOOK OFF HIS SUSTENANCE RING) and can't just do that part again. But all that has got to count as Treat Deadly Injuries, which is good for another 17hp -- Merrin has got to be making these rolls by more than 5 -- plus 17hp of nonlethal damage cured too...
Which amounts to a total of 29hp of lethal damage cured, and 29hp of nonlethal damage...
And that's not gonna take his total lethal damage + nonlethal damage under 87, because Esta was frankly not doing totally great with all that underwater battering before he drowned.
Next up on Esta's potential healing schedule: A full day's rest, or Long-Term Care if some Healer cares to put in 8 hours of light work about it.