Correct, penny stocks can be shorted. However, the price per share seems to matter. At what point is it not feasible to short a ticker? At $1.00? .50? ..20? (What is the lowest share price that Timothy Sykes has shorted?)
Anyhow, here is some additional info on shorting I have come across:
Interactive Brokers has a percentage requirement or $2.50 per share, whichever is more. If you're shorting stocks that are around $1, you're paying more in fees than you would be for the position.
Ultimately, you can believe what you want, of course. Not going to debate it.