I love my electric bike, and largely agree with the sentiment of this article. My bike has has saved me a fantastic amount of gas.
However, I think calling them the "most climate friendly" is reasonably accurate, but has some issues.
If you're including the human power, a regular bike is more efficient electrically, using none, but the calculation for climate friendly is much harder.
If you're not, there are more aerodynamic electrical vehicles that are more efficient, but given their rarity, I can understand why they're not included.
If you're not including human power, the other more common electrical vehicles, scooter, onewheels, etc. Are likely about the sane efficiency, but have less environmental costs to make (smaller) and can be integrated into many peoples lives easier.
It's a tricky blanket statement to make.