Have you tried to play that turn without script activated? Otherwise you could cheat:
<add_population><space><"><settlement_name><"><space><value>

Which would result in:

add_population "Gordu-Neujuri" -7000

Or something like it (as you see you may enter negative values there, and as for the actual size of value: it's a matter of trial and error and you'll see what value works best). Reducing the population size should increase the Mak garisson impact on public order, which in turn should prevent the province from rebelling. Hope this helps, if nothing else does.