ToolTimeTim7 Afaik aosp, stock etc also do ahead-of-time, but only on major Upgrades. Question is: why is it useful to do this every time?
As clearly evidenced in the threads reporting on leaked Cellbrite documentation, GrapheneOS is more secure than Google's stock Pixel OS. So expecting GrapheneOS to do (or not do) things the same way as the stock OS is somewhat contradictory.
As another example, the GrapheneOS memory allocator paves over memory more often than the allocator on the stock OS.
I don't know exactly why GrapheneOS recompiles applications on every update. But I can readily imagine that somebody inside Google might have figured that recompiling less often would be a better user experience while being "safe enough". And I can readily imagine that the GrapheneOS authors decided it would be better to be safer instead of "safe enough".