I guess whether it is sad (chilling effect) or exciting (prevents abuse of paradox of tolerance) depends on your perspective on the particular issue, but the principle here is a non-citizen is a non-citizen. They should not get other ideas. There are many legal activities that non-citizens cannot do: namely they cannot engage in work without authorization, for example. LPRs are given more leeway but those are all within the realm of INA itself not constitutionally protected. What INA giveth INA taketh away.
I understand. My point is that, if one of our founding principles is that government overreach should be defended against and thus constrained--a principle that guides our Constitution and is enshrined in the Bill of Rights--it really shouldn't matter whom it's protecting. Fenceposts don't move when a horse tries to get through instead of a cow.
To be fair, the Court did not hold that aliens aren't protected by the Constitution. It avoided the question by holding that the aliens' activities weren't protected, and that Fifth Amendment protections are different (and less stringent) for civil process than for criminal process.
I think the alien is still protected under First Amendment in the sense that you cannot criminally charge him of a crime. It simply has a consequence as outlined in the context of INA, losing a benefit that is obviously not applicable to the US Citizens in the first place, just like a US Citizen could lose a public job (Garcetti v. Ceballos).
