The Quibbler? He didn't hide his snicker but didn't exactly laugh so hard that it was incredibly rude. Marcus couldn't help it though, the Quibbler was not something he supported, none of his housemates ever really did and his family certainly did not.
Marcus figured she was harmless then, wouldn't blab too much about his condition.
"Marcus Flint. I play for the Falcons... but my vision is going. I've had the best healers working on my eyes for years now and the charms and potions don't tend to work well, if at all."