"No player may call defensive signals that simulate the sound or cadence of (or otherwise interfere with) offensive starting signals ."
Again, some of you are reading the parenthetical as an independent statement. It is not, it is descriptive of the preceding phrase.
Read the rule without the parenthetical phrase:
"No player may call defensive signals that simulate the sound or cadence of offensive starting signals ."
The "otherwise interfere with" does not stand on its own, it is meant as a further descriptor of the preceding phrase. So the defense cannot simulate the sound or cadence of the offensive signals in order to interfere with the offense. We all agree that would be a penalty.
But there is NOTHING in the rule that prohibits the defense from calling their own signals which do NOT simulate the sound or cadence of the offensive signals.