They intentionally leave it ambiguous. From what i have gathered, they will look at trade frequency, whether you have a busy day job and income from stocks relative to your day job etc, to determine whether your stock return is considered taxable income or capital returns. It also applies to property investment / flipping. If you buy and sell properties frequently, even if u have held it for more than 5 years (to get zero RPGT), they can still consider the capital return as taxable income.

Yes, the capital gain is considered income as he bought and sold too many properties too often.