I think “not for long” is fine, Jar Jar. Poe says it while Pryde is resetting the nav tower, so it is down for “not long.” Finn hadn’t managed to destroy the signal, he just temporarily deactivated it. Doesn’t it power back up in a minute anyway? I honestly can’t remember.
That all kind of proves my point though that the battle is about the nav tower rather than the command ship. Finn only decides to blow up the ship because they’re resetting the nav tower - he doesn’t do it on a whim, he does it because it’s the only way to make sure that the only operational nav tower is destroyed.
Now, whether or not restarting your computer can fix it after it’s been blown up with grenades, that’s a different question entirely.