Well in the update once you compost the staff you get your speedrun time. So the lava method only works for killing the boss, not actually beating the category. And yes there are other ways to cheese the boss but it would still be a fun thing to add to the sub-categorys of 24w14potato.
Okay after reading the rules for the entire speedrun.com site. I do see that you must show the pause menu before or after your run. But also I still think time should count while your atleast doing it at the start of the world. When my speedrun's time got edited the Mod CZX commented saying "(For future reference, timing starts on world load, not first input.)" Therefor that should be applied to all speedruns.
I feel that if your doing a speedrun, the time starts when you load the game. And not when you unpause the game. And yes i didnt know this was a thing when I started speedrun 24w14potato i think that the way the time scoring works is that when you load into the game the time starts no matter the pause menu or nothing. Like In Hayley's run they are at the pause menu screen for a solid 6 or so seconds before the time actually starts. Or in Mandsa's run where they use the pause menu screen to get the exact frame where the pedestal actually teleports you. (No hate to any of them btw) Just saying that I think this should be change or atleast state it in the category rules.
poisonous potato blocks can spawn in cobblestone amethysts so you would only need 729 of those blocks in order to complete it.