Solomon Islands Pijin is not a pidgin?

Long story short it used to be a pidgin and the name stuck. {I]Pijin[/i] (along with Bislama) is related to Tok Pisin. According to the SIL Ethnologue (link) it has about 25K first language users and around 300K 2nd and 3rd language users. That makes it a creole in my opinion, but it also states that it is in the process of creolization. You might want to read Dell Hymes, Robert Hall, or John McWhorter on pidgins and creoles. (Cf. the confusion in calling many of the Chinese languages, e.g., Mandarin, Hakka, or Cantonese, dialects when they are in fact languages and mutually unintelligible.)

It's like trying to distinguish between a language and a dialect, or the latter and a cant, jargon, or patois. (Famously) a language is a dialect with an army and a navy (link). Patois is a French synonym for dialect, and a cant or jargon is a specialized vocabulary used by certain groups, e.g., soldiers, thieves, IT professionals, antique dealers.

Ceci n'est pas un seing.