If you had a real time monitor of the coders and code they would still cry stealth changes, it a meme now for better or worse.
Also pretty sure nothing has changed with chem bombs for a while. The nade in OP probably had all the impact hit the researcher or something or just a one off incident or maybe rav pounce just before nade went off who knows. Chem nades still scare aliens since it can always be a glorified m15 in a can.