The article explains why this is not as simple as that, especially in the case of timing attacks. Here it's not just the end-result that matters, but how it's done that matters. If any code can be change to anything else that gives the same results, then this becomes quite hard.
Absolutist statements such as this may give you a glowing sense of superiority and cleverness, but they contribute nothing and are not as clever as you think.
The article describes why you can’t write code which is resistant to timing attacks in portable C, but then concludes that actually the code he wrote is correct and it’s the compiler’s fault it didn’t work. It’s inconvenient that anything which cares about timing attacks cannot be securely written in C, but that doesn’t make the code not fundamentally incorrect and broken.
Absolutist statements such as this may give you a glowing sense of superiority and cleverness, but they contribute nothing and are not as clever as you think.