This is a great idea .. I wonder if it can be adapted to using recycled plastic threads, so that a fleet of these could be deployed into the ocean to recover plastics, turn them into nets, and use those nets to .. recover more plastic?
If I were shipwrecked on a tropical island, I'd make it my daily task to work out how to build something like this, into which I can feed plastic bottles, and get a brand new material that could be used for more construction.
Sure, knitting scarves is neat. But knitting a weather-proof shelter? Hell yeah!
To recycle plastic, the only viable way is to melt it. And the plastic must be very clean before it can be remelted. If it even is a kind of plastic that can be reheated multiple times. I am afraid the short answer is no.