I did this trip as an overnighter about 10 years ago with a buddy. It’s a great mini-adventure.
As Craig says, nearly the entire Los Padres NF is technically closed right now (the closure is tentatively scheduled to be lifted in ~10 days) due to extensive Jan. storm damage. My recollection is that the trailhead area at Piru Lake is also closed (which is likely why the trail/route may be listed as closed). In the past when the Blue Pt or Pothole trailhead parking areas were closed (for years), this just meant you had to walk a few extra miles to the nearest legal parking spot adjacent the boat ramps at Lake Piru. I’m not sure if this is how it’s being treated still or not. A call to LPNF or Lake Piru campground might sort this out.
The last item I’ll share, while not giving too much away, is that this trip is HIGHLY dependent upon water levels. We’re well over average rainfall for this year, so I expect water levels to remain high well into spring. It wouldn’t take much extra water for the crux of the trip, passage through Piru Gorge, to become impassible on foot. There’s no way through the gorge except straight down the creek.