I am skeptical how worthwile it is to use /e/os over OEM Android at this point

Agree with your outlook, but I think it's not too farfetched to give the benefit of the doubt to the speaker here and establish that pedophiles were used as an example (of people whose survival depends on their data not being breached), rather than a direct comparison. And he goes on to name being an executive to the secret services as another example (again, of people to whom hardened security of data is an imperative), but we're not saying he thinks secure phones are just for people in secret services, are we?

He's just saying, albeit rather clumsily, that their goal is simply not that level of hardened security, but rather privacy from data miners.

I think both approaches are too extreme. Supporting every device leads to poor security, poor stability, and therefore a poor user experience, but only supporting just Google devices (while there is a good reason for that) is a step too far for most people.

If I were in the position of e/os I'd just support probably three manufacturers. Going through the major ones that I know of: Motorola and Google are obvious picks. Next would need to be something cheap and popular. Samsung is way out of the question. Xiaomi and Vivo I've never seen their phones mentioned outside of China (which is a country that generally doesn't have the same privacy considerations as people in the west do). That leaves Oneplus and Tecno Mobile for the third model.