Not only does he know that "it's" is a contraction, he also knows what a dangling participle is. (Be still my heart!)
Now that I am backed by a celebrity, I feel inspired to add my own Word Crimes:
1) Impact is not a verb. It is a noun. You can have an impact on something, but you can't impact it. (It may be true that all your friends, TV announcers, and anybody with an MBA believes impact is a verb. THEY ARE ALL WRONG!)
2) "Issue" does not mean "problem," it means a topic of debate. You can discuss an issue, but you cannot have one. (This grammar crime was fomented by therapists, who also have convinced susceptible individuals that they can be "conflicted" when they have "issues.")
3) Grow is what you do with potatoes - not audiences, businesses, or twitter followers. (This is an MBA crime.)
4) "Conflicted" does not exist. You can feel conflict, you can even be in conflict, but you can't be conflicted. (See number 2 above.)
4) Disrespect is not a verb, it is a noun. You can show disrespect, but you can't disrespect someone.
5) "Different from" (or "different to" in Great Britain) is correct when you are comparing nouns, not "different than." For example, California is different from ... well, just about anywhere.
6) The object of a preposition is object case, not subject. Let's keep this between you and me, not you and I.
7) "Like" is for comparing nouns. "As if" is for verb phrases. I act like you, but we can't act like nothing matters. We must act as if nothing matters.
8) Plurals do not use apostrophes - EVER. You own CDs, not CD's.
9) A possessive goes with a gerund. "My going to California upset her" is correct, not *Me going to California upset her."
10) Reported speech uses declarative sentence structure. "I asked him what the time was." Not *"I asked him what was the time." If you are quoting, you can use interrogative structure. Ex. I asked him, "What is the time?" (Reported speech is comprised of sentences beginning with phrases using verbs such as wonder, consider, ask, etc. Ex. I wondered what the time was. I considered what the alternatives were.)
If you are guilty of any of the above grammar indiscretions, you are doomed to suffer the eternal torment of grammarian hell. Also, people will assume you did not pay attention in my English class. (That's right. I'm talking about you, Pete.)