A cougher should only be told once, after that, 30 days! If the cougher has children with them, they should immediately be put in the custody of child protective services.
Nice try with the hyperbole, but you know that's quite a different situation. People might not be able to control their coughing, so a judge should give them more leeway until it becomes clear that they cannot control it but are still unwilling to leave the courtroom.
The same logic does not apply to cell phones. Everyone can control their cell phones. For a rational person, one warning from the judge should be enough.