I was being sarcastic, largely because people on HN have vigorously opposed my assessment that time working for a startup at below market rates is fundamentally the investment of money in that startup.

So at minimum every "employee" working for a startup is investing (market rate - actual rate) dollars in that startup. That's also not super equivalent because time investments (and standard employment contracts) mean that there is an absolute opportunity cost to working for a startup that does not match a cash investment. Essentially you can invest money in multiple companies at a time, you can't invest time repeatedly.

I think they were being sarcastic

correct, I had thought in this context at least it was obvious :)