Visa is not a currency, just a means of payment / moving currency. Visa does not issue currency. Bitcoin is a currency which happens to implement the means for its issuing and moving between "accounts" (addresses).
Visa's underlying currency (fiat) uses *zero* energy (paper notes).
You are assuming that the coins never will be inside a Bitcoin bank in the future. A transaction can occur off chain.
You just described a cash transaction, requiring *zero* energy.
In addition to some of the other very valid points above, your comparisson seems to be focused solely on electricity usage and only considers the 2 Visa data centers in that evaluation and ignores the millions of always-on POS equipment required to actually transmit data to those centers.
The comparison is valid. He's also not including the energy used by non-mining boxen & their monitors. Try dealing inn bitcoin with just headless miners.
On a slightly sadder note, he's also not factoring the bitcoin POS devices 'coz ... there's only a handful of B&M business accepting bitcoin. Or do you suppose large retailers will use their cashier's smartphones as bitcoin POS thingamajiggers?
Furthermore, in that same article you linked, it is estimated that *one* of these data centers costs "hundreds of millions of dollars" to build, and at 8 acres in size, I'm sure it's staffed by many employess, who probably demand some kind of salary for working there.
Bitcoin, with only a billion dollar market cap, has already spawned many multi-million dollar ASIC companies & commercial miners. And bitcoin is not serving a fraction of a fraction of a speck of transactions handled by Visa.
Then when you consider that all of this is just to provide Visa services, which is only one aspect of the financial system, you can *maybe* start to see how you are comparing apples to dwarf stars.
How much bitcoin value is exchanged for goods and services daily? And how much dollar value through Visa? Let's not kid ourselves -- it doesn't work, we're not that stupid.
