It seems that they've also talked themselves into believing that running extensions in the main process has all of a sudden become totally unsafe and absolutely irresponsible, while at the same time the solution employed on desktop (run extensions in a separate process) unfortunately isn't possible because on Android secondary processes might randomly be targeted by the low-memory killer at any time, which would break a lot of add-ons.
So a few extensions have been grudgingly permitted with extra scrutiny given during review, but they don't want to extend that effort to all add-ons, they don't want to back down to accepting the previous level of security, either, Android won't change its handling of child processes (and even if – any change there would take years to percolate throughout the phone ecosystem, plus a number of OEMs somewhat infamously are even more aggressive about killing seemingly unused processes), and re-architecting add-ons to cope with randomly being killed isn't an easy and immediate solution either.
So a few extensions have been grudgingly permitted with extra scrutiny given during review, but they don't want to extend that effort to all add-ons, they don't want to back down to accepting the previous level of security, either, Android won't change its handling of child processes (and even if – any change there would take years to percolate throughout the phone ecosystem, plus a number of OEMs somewhat infamously are even more aggressive about killing seemingly unused processes), and re-architecting add-ons to cope with randomly being killed isn't an easy and immediate solution either.