This fallacy gets pointed to constantly, but it's not actually part of most arguments. I.e. it's a strawman. Bad immigration policy can and does negatively affect opportunities and salaries. Immigration in general does not necessarily do so, and an argument to that effect would be an example of the Lump of Labor fallacy, but that is not the argument being made.

I'm responding to the argument made in general, yes, if you read the post I was responding to.

> Bad immigration policy can and does negatively affect opportunities and salaries.

It is true by definition that some immigration policies are worse than others — for example, a policy of no immigration at all (which is a kind of immigration policy) would be very bad for opportunities and salaries.