Why would a nonprofit organization like Planned Parenthood turn down a $500,000 donation?

Because PP isn't about helping women find affordable health care. It's all about pushing a far-left political agenda.

From columnist Gil Spencer:

The main reason that PP doesn’t need Tucker’s lousy five hundred grand is because it already gets hundreds of millions of dollars from YOU, the American taxpayer. Every single year. Tucker’s half a mil is chump change to the billion-dollar, taxpayer-subsidized operation that is Planned Parenthood.

Gil Spencer: Planned Parenthood aborts donation