Can anyone explain the reasoning behind it? I can understand (not saying I approve) targeted opposition to specific scientific claims to favor commercial interests (climate change denial to favor oil & gas, etc), but wouldn't a general anti-science movement make the country less competitive in the long run and directly hurt industries like pharma/etc?

Punishing apparent ideological enemies is a long standing mechanism for fascists and dictators - and scientists in the US qualify. It's an attempt to make people fear standing against them.

Destroying sources of truth is a long standing goal for those who want people to act against their own interest, and scientists are a source of truth. It's shrinking the pie so that the republican leadership can capture a much bigger slice of it.