I don´t see how he insulted, he´s just pointing a fact. Voiceover quality is not exceptional.
Fiverr is not a direct competitor either, you can get all sorts of things there apart from voiceovers, for example you can get book covers, video recordings of people writing whatever you want on their body, pictures of your logo in front of the taj mahal... its quite cool.
There's a massive difference between highlighting your USP and insulting your competitors.