Earlier quoted context omitted.
can you elaborate on this capital gains tax loophole?
Long-term capital gains are taxed lower than normal generic income (at rates lower than the same person would pay in income tax) which in turn taxed lower than labor income (which is, in addition to regular income tax, subject to payroll tax.) Closing the capital gains tax loophole is, presumably, a reference to stopping some or all of this favorable treatment.
2. Changing that would not do anything to solve this problem (even if you think it should be solved through more government spending, it wouldn't raise much money)