I would say that if you care about the aviation history of this country and the freedom we have to fly general aviation aircraft now, or in the future, then you must be a supporter of AOPA. Being an airline pilot makes zero difference. The airline trade groups can fight for what they want, but most of the pilots of those aircraft come from a general aviation background.
To become a pilot in the USA is relatively easy compared to many other countries. Some places, like Taiwan, still have an outright ban on general aviation of any kind. Many countries place very high costs and numerous restrictions on general aviation. If it wasn't for general aviation I don't know that I would have been able to start on the career of my choice.
I would hate to see the USA go down that road and that is exactly what the airline trade groups would like to see. Just because I am an airline pilot doesn't mean that I should turn my back on my roots. Not me, that would be like turning your back on your parents after they raised you.
AOPA has a strong voice in Washington to help keep general aviation thriving in the USA. Are they perfect?, no, but they help to preserve the freedoms that the U.S. enjoys in regards to flying and to those starting on the path to an airline or corporate career.
If you really can't stomach AOPA then at least join the EAA as they too fight to protect the interest of general aviation in America.
Typhoonpilot