The article is indeed correct. After going through several discussions and talking with various experts, I'm finally certain about the language of Section 115BBH. It only deals with the trading income. If you are earning crypto from any other activity, it doesn't come under the ambit of Section 115BBH. However, such other activities give rise to two taxable events. Let's take an example to make it more clear:

One of the items in the table above is 'Getting paid in crypto' which includes campaign payment on the forum. Suppose a participant receives $100 weekly in BTC but doesn't immediately sells it. Finally, he sells his annual income after 50 weeks which should be $5000 in BTC but due to the fluctuation in the prices of BTC, it stands at $7000. It is clear that $5K out of $7K is an earning from the campaign but $2K is the profit from speculation. Hence, $5000 at USDT/INR rate on the date of sale will be taxed as per normal taxable rates whereas $2000 at USDT/INR rate will be taxable at 30% under section 115BBH.