I just had a brain-flash as to why not as well...

Even supposing that Don had considered it, (which Gryph has noted that he probobly wouldn't) a quick scan of Scott's Cerebro records revealed that the part of the brain that controls humor had been the part that mutated into the 'generator' for his eye blasts! This hand wave actaully works on several levels, in that a bio implant wouldnt work to add a sense of humor, and it gives a tradeoff... Scott could have a sense of Humor OR his optic blasts... and has chosen his optic blasts instead. ;)