And specifically, to make that choice for them?
Caveat hacker.
"Here are the things I know" + "Here are the things I know I don't know" + "Can you help me?"
I'm sure there's a ton they don't know they don't know (stranded vs solid core AWG equivalency), but this is a pretty simple use case -- running power a relatively short distance in a temporary install.
The worst that can happen is they or someone on the street short across their heart and dies. Which would not only require shocking yourself, but doing so in a pretty specific orientation.
But they're already in a warzone! That risk is lower than their base level of environmental lethality.
The Stack Overflow poster is on a metaphorical hill in a literal warzone to literally die on. They're trying to hack together AC power the best they can to make their home in Sudan livable. That's some serious hacking! So what if they don't know V=IR?
"You shouldn't use that sort of electricity, you should switch to three-phase."
"How can I do a thing?"
"You shouldn't want to do that thing."
Danger/risk is a situation that happens sometimes, but it's never an excuse to dismiss the asker's question and need.
Explain the warning or concerns ("May catch fire and explode" or "Will not be to code, would cause your building to fail inspection" or "There's this other framework/language that might make it easier"), but also give them a damn answer!
In this case, there's no @$&#ing reason someone sitting in their office shouldn't do the calculation that's being requested from the parameters supplied. It's a simple emag calc.
I'm pretty sure stackX would tell someone asking about the time required to boil water for sanitization to never drink boiled water and use the tap. :/