^My bad, I just read "jakarta" in that link and thought you were talking about the other crash.
As for "they shoulda untrimmed," if you look carefully at this report, there's nothing in it that proves the pilots did not do what you are suggesting they should have done. The report does not include the duration of the pilots' trim inputs. Only the resultant change at the stabilizer. It is quite possible that the pilots pressed the button appropriately, but the stabilizer did not move the amount that would be expected, due to extreme elevator load. It appears they may have "neglected" to switch the power back off, though.
After the Alaskan Airlines 261 accident, the NTSB has suggested that in a case where the trim is not working, properly, that no further attempt should be made to correct the trim. So what they "should have" done is not exactly clear without having been there, unless you have a crystal ball. Even if there were able to maintain level flight at that point, with no further trim adjustments, that doesn't guarantee the plane could bank to return to the airport without losing too much altitude or that they could land the plane, safely, in this condition. They may have had to land at a much higher than normal speed, and they might not be able to stop on the runway or they might break the front landing gear. Depending on the airport, this might mean crashing into buildings or a mountain... or falling off the edge of a cliff. This airport has been described as a shoebox in the mountains.
*I find it rather curious that the report states the duration of the MCAS response a couple of times, but nowhere does it state the length of trim input from the pilots. I find it hard to believe this is not recorded by the black box. Perhaps the response was not appropriate, and the airline is intentionally omitting this information to keep this data hidden for a bit longer.