As mentioned in the article, it's sacred to the highest tier of PlayStation's new subscription service, so they won't remove it.
OtherOS came with the system in the box, and Sony tore it out after consumers had already purchased the system.
A subscription service, they can just end it and refund people's money and call it a day. It's absolutely not set in stone.
Unless they decide the revenue from the highest tier is worth leaving it in place. To be determined.
With PS2 emulation, I suspect far more people do use it and it would be much, much easier to prove you used it. This could lead to a huge settlement against them.