The student doesn’t need to explain what the new penalties are. Instead, he needs to explain why they’ll be ineffective. Even if he did specify them, his argument would still be flawed because he assumes the new penalties will fail simply because past efforts did.

The student doesn’t overlook this possibility. Many students at the university may not drink at all; the penalties only target those students who do drink in on-campus housing.

The student doesn’t assume that students prefer to drink on campus, just that some students do drink on campus. Whether students prefer to drink elsewhere is irrelevant; the penalties only target on-campus drinking.

The student assumes that the new penalties are relevantly similar to the university’s past attempts to curb on-campus drinking. If they’re relevantly different, he can’t conclude that the new ones will be ineffective simply because the old ones were.

It doesn't matter whether the new penalties have other positive consequences. The student only addresses whether these penalties will effectively reduce drinking in on-campus housing.