Not having ever heard of the Gibbs penetrant I shouldn't make any assumptions, but after reading the sales blurb, "Too good to be true" comes to mind.
Having painted many cars and bikes over the last 30-odd years I was surprised to see the comment that "You can paint right over it", so it seems a little hypocritical to later to see that there is a disclaimer, right at the end of the "article", that I'll quote here:
Painting over Gibbs Brand
"The label on a can of Gibbs Brand says that "you can paint right over it". However, common sense will tell you not to paint over an oily surface that isn't clean.
To paint metal that has been treated with Gibbs Brand,
simply begin by wiping it down with whatever surface cleaner is recommended by the manufacturer of the particular paint system that you are using, and proceed as you normally would.
Due to the tremendous variety of ingredients that are used in paints, it is not possible to be absolutely certain that Gibbs Brand is compatible with every paint on the market. However, we are not aware of any compatability issues with any particular paint."
The second paragraph seems to confirms my suspicion. You need to remove the Gibbs product with "Surface Cleaner" (AKA Prep Solvent, Wax and grease Remover, Solvent wash etc) before you can paint over it, obviously negating any benefit of having it there, because of course, once it's been washed off with solvent, it's not actually there any more..................
I'm sure it's a great alternative to WD40, but I doubt that it's the Holy Grail. Cheers, Terry.