Yep, it's pretty much a cameo. This is The Odd Gentlemen's equivalent to AGDI's The Madness of King Graham, basically. The difference is the game and Graham telling you you're a terrible person for wanting to abandon owlet Cedric to a grisly demise. The POISONOUS reference is there to toss in both the arguably most "iconic" annoyance of Cedric as well as the consistent retort.
Personally, I'm far more amused than annoyed.