While the headphone issue is problematic, it's a single issue amidst a deluge of ethical and sustainable practices by the company. Including, but not limited to:

Fairphone carefully sources the components in every device, and the workers who put them together have safe and healthy working conditions. Where possible, Fairphone uses recycled materials (plastic, tin solder paste, steel, and nickel alloy), sources Fairtrade gold, and buys cobalt and silver credits to support the improvement of working conditions for miners.

The factories that make the Fairphone pay a living wage to workers. It also employs 100 percent renewable energy. Fairphone invests in projects to reduce CO2 emissions, and to balance bringing a new phone into the world, Fairphone recycles the equivalent amount of e-waste. It has a B Corp certification, which means its claims have been independently vetted, and Fairphone regularly releases impact reports.

(As reported by wired.com)

Absolutely they should get push back on the headphone situation. But calling it "greenwashibg marking bs" is textbook "letting perfect be the enemy of good". Simply put, almost no other company even competes with Fairphone in the field of ethical phone manufacturing.