This is irrelevant and doesn’t justify the author’s argument. First, this doesn’t bridge the gap between preference and bitterness that we identified. Second, this is comparing supertasters and regular tasters, when we need to compare them to nontasters.

Age is irrelevant: we don’t know if there’s a difference in age between the taster groups, and we still need an assumption bridging the gap between bitterness and preference.

The argument’s conclusion is about whether certain tasters find certain cheeses bitter, so sweetness is irrelevant. (Basic tastes, like sweet and bitter, are not mutually exclusive; foods like chocolate can be both sweet and bitter.)

Supertasters prefer mild to sharp cheddar. Nontasters have no preference. If bitterness is the only relevant factor, supertasters must perceive sharp cheddar as more bitter. And non-tasters must not perceive a difference.

This doesn’t bridge the gap in the argument between cheese preference and alleged bitterness. Without a connection to bitterness, the variety of foods different kind of tasters like is irrelevant.