Bad reasoning there.
Insta-gib is short for "Instant Gib"
The only soft G that begins a word that I know of is George and personal nouns are usually excluded as ways to prove how something should be pronounced due to the personal connotation to it. Golf, Gold, Great, Get, Grape. They are all hard G's. That is why Insta-Gib should be Insta-Gib, not Insta-Jib.