Elon probably told them to dump the coolant in the street because he thought it would be a very funny joke. And probably also told them to put the green dye in first.
Sounds like the sort of thing he would think is hilariously funny.
Lye and oil makes soap, not lye and borax. The key in all these recipes is lye and oils, not lye and borax for anyone who isn't going to click on the link and start mixing these chemicals. Lye can be real nasty if you don't know how to handle it. It's one of those chemicals where the safety precautions are there for a reason, not because it's normal practice.
could have been a kind of additive maybe? but then it won't be a lot of it. borax forms a gel or at least high viscosity solution when mixed with glycols so both can't be used at the same time as a coolant
Dye might be fluorescein, it fluoresces under UV (duh) could be useful in checking what's this thing
It's possible they didn't properly treat the liquid they were using as coolant and needed the lye and borax to remove scaling and that it actually wasn't the coolant itself. That would also explain not having the proper permits for storing the chemicals if they were just being used for cleaning. Though wouldn't be surprised if they were then just going to dump it down the drain anyway...