I disagree with the author on this one - a few years ago someone was caught in the act stealing a Vectrix (reported on a different forum).
But mostly - as electric bikes get more popular and well-known - and as people hear more about Tesla and how cool EVs are in general - I think they will be an increased target for theft. For the value of the batteries, yes, but also for the bikes themselves. The author of the article sounds a bit biased against electrics, with the attitude of, "why would anyone want to steal one?" Ha!
From another perspective: some thieves base their decision, not on how to sell something on the black market later, but simply on how easy it is to steal. I had a beat-up old Ford Escort that I used for commuting that was stolen in broad daylight. Why? Because a couple of high teenagers wanted to go for a joyride and it was the easiest car to steal. It had no value on the black market, indeed it turned up a few weeks later, destroyed, and had to be towed to the junkyard.
Zeros are lighter than their gasoline counterparts - therefore easier to steal. Maybe time to install a "LoJack" or some such :-)