No. This is inside the handleIntent() method which is like a main entry-point inside that Activity. And the intent being handled here is the ACTION_SEND. In simple words, when a message is being sent:
Intent.ACTION_SEND.equals(intent.getAction()))
And no, it isn't just removing "Sent from Whatsapp", it is setting the sendingText variable to null, which will result in:1. The message not being delivered.
2. The exception block being fired where this toast message will be displayed to the user: "Unsupported content"