I don't think this is real. I think somebody has tried to copy the signatures from another piece. The Chris is not right, Dave's signature is not in his style of writing out his block letters and the Kurt is difficult to say 100%
I think people need to give up on the idea of obtaining something signed by Kurt. I love Nirvana, I love autographs.
I will never own a Nirvana autograph. I've accepted that, Its one of those that is just impossible to verify unless there is a photo of Kurt signing the exact item and iron clad provenience. Even then you are looking at like $10K. 1% are real and 99% are forged. PSA is useless in these circumstances.