For anyone who flies, aviation is a huge fraction of their personal emissions. It isn't about "targeting aviation." Just any individual (who isn't an anarchist) should reduce their flying. But as you say, they should also reduce their emissions from ground transportation.

Beyond the personal, on the broader political scale, I also don't know that targeting any particular thing makes sense. All emissions, from all contributors, need to fall. Something like a carbon tax would cleanly attack the least efficient carbon emitters first.