“All they did was rehydrate the contents of the ink sack with ammonia and voila, ink!”
No. you can’t “rehydrate” with ammonia, only water, which obviously didn’t work.
If it took ammonia that tells you that the ink does not degrade in water and requires a solvent that was not present in the fossil.
I’ll bet they could make “ink” with any number of solvents.
You are obviously not familiar with common lab techniques.