Ok my rudimentary attempt at the sums.
We have to combine 2x EV equations because of the side pot.
The range for button jam is huge but I've played around with it and even the very conservative range of..
22+,A2s+,K7s+,Q7s+,J8s+,T8s+,98s,A2o+,K9o+,Q9o+,J9o+,T9o
which is top ~35% of hands, combined with an equally conservative range for SB of..
22+,A2s+,K9s+,Q9s+,J9s+,T9s,A6o+,KTo+,QTo+,JTo
Which is top ~25%
Against those ranges 77 has ~
33% equity in the main pot and ~
53% in the side pot versus the SB
Stacks are..
Btn:
55000SB:
168000BB: 260000
Main pot =
.33 (55000+55000) + .67 (-55000) = -550
Side pot =
.53 (168000-55000) + .47 (-111300) = 6780
EV = 6230
So clearly Jamming is +EV without allowing for SB to fold <0%
There is most likely some ICM consideration at play in this spot too and it would be great to see some attempt at that, sadly it is a step beyond my limited capabilities