In Rodman Philbrick's novel Freak the Mighty, Max is not so much bothered by Freak's speaking as he is amazed by it. Max has never encountered anyone who speaks like Freak, whose real name is Kevin. There is no textual evidence to support that Max is bothered by his speech. Consider the following quotes:
"That's how he talked, like right out of a dictionary. So smart you can hardly believe it. While he's talking he's winding up the bird-thing. There's this elastic band inside, and he goes, 'Observe and be amazed, earthling.' And then he lets go. And you know what? I am amazed, because it does fly just like a little bird, flitting up and down and around, higher than I can reach."
"This is the first time for me, hearing Freak really talk, and right away I know one thing: when he's talking, you can't take your eyes off of him. His hands are moving, and it's like he's really seeing it, this story about an old king."
"I think so, but I like hearing Freak talk, so I go, 'better tell me,' and that's when I find out why he's so interested in some clanky old knights."
These quotes show Max's awe of Freak's vocabulary and speech, but don't support any irritation he feels with Freak's speech.
Freak's vocabulary is incredibly advanced, and certainly beyond Max's experience. Freak does a good job explaining the words to him, and Max is able to pick up others through the context of Freak's speeches. Here's an example:
"Pardon my vocabulary. Sobriquet means 'nickname,' and demeanor means 'expression.' I merely postulated that you call your grandfather 'Grim' because he's grim. Postulate means—'
'I know.' I say. Which is a lie, except I can guess what he means, figure it out that way.
Considering Max's learning disability, and subsequent dislike for books, it would be reasonable to infer that Max is bothered by Freak's speech; however, an inference must use the textual evidence plus the reader's background knowledge to form an educated guess. The textual evidence doesn't support Max being bothered by Freak's speech.