Here's my experience with tones on radios that have annoying squelch tails. It all depends on the radio system.
If the tone drops off before the carrier does (example - Calif Highway Patrol in LA County), then the mute circuit will kick in (due to the tone drop-off) before the squelch tail can be heard. However, if the tone drops off at the same time as the carrier (example - Calif Highway Patrol in Orange County), then the radio squelch tail will be heard before the mute circuit kicks in.
In the old analog radios (like the crystal scanners), you could easily eliminate or adjust the squelch tail by simply removing or replacing a capacitor. Can't do that with modern computerized radios. Radio manufacturers should make the squelch tail user adjustable, just like the delay time and all the other user-adjustable parameters.