The carbon footprint point was based on false data. Energy requirements of BTC were greatly exaggerated.
It is based on untrue 'research' published by the site bitcarbon.org, which is referenced by the source article you link to.
Bitcarbon based their entire calculation on a wildly-inaccurate, very outdated guesstimate of power consumption they found at https://blockchain.info/stats
Clearly neither Bitcarbon, nor the source, made any effort to verify this number (despite a note at blockchain.info pointing out that it is probably not reliable). This totally undermines their data and brings all of their claims into question.
The fact is that the hardware that Bitcoin transaction processors are using today is 50-100x more efficient than it was a year ago. Although the difficulty of the work is increasing, the power consumption is not. In addition, far less power is being lost as waste heat.