Dokutsu-Rutake proves that some Poison Mushrooms' abilities can have a beneficial side to them, and fungi are often a vital part of healthy plants and ecosystems, so it's likely the lab in question was doing experiments to isolate beneficial abilities and duplicate them.
Also, if you suspect someone hates your guts, don't drink or eat anything they offer you, especially in a story where a lot of characters have essentially poison-based abilities.