what purpose does Odysseus's encounter with Melanthios serve

Odysseus wants to remain disguised. When he first meets Melanthios at the fountain, he isn't recognized, and Melanthios kicks him. Later, he pretends to know nothing of him and treats him as a stranger, helping Odysseus in his quest against Penelope's suitors. Melanthios would never have disrespected his master or shown disloyalty had he known it was Odysseus.