Why's a penny stock basically a call option with a strike price of 0 that doesn't expire?
Your misunderstanding comes from the fact you are treating a penny stock as an option. They are not the same this is just a metaphor. The difference that makes the difference here is ownership.   

The reason the strike price would theoretically be zero is, for a penny stock you own the underlying asset, so you would not pay to own something you already own. A strike price is how much you need to pay to purchase the asset, but you own the asset in this case.

The OP Reddit poster is dead wrong and is referencing a huge amount of underlying assumptions about penny stock trading and options trading. You can't treat them as the same.