It's not a conspiracy theory. Dave Dunipace himself has said he loves GStar plastic, he carries GStar plastic discs himself (shown by video of him playing as well as his own answers in the AMA video), so it's no great feat of deduction to know that Dave Dunipace loves GStar... and therefore no big surprise that Innova (controlled by Mr. Dunipace) puts out a lot of molds in GStar and promotes that plastic.
Also, 'conspiracy theory' suggests that something is wrong or illegal about it. Nothing wrong with Mr. Dunipace and his company putting out molds in whatever plastic, so I'm not promoting any 'conspiracy' theories.