I don't think he means no interest for traditional character sets. Pleco can detect both simplified and traditional just fine with OCR. It's just the extremely rare ones that it doesn't do. These Cantonese characters are considered rare because a lot of them were made up just for it, so they are never used in Mandarin Chinese.
I feel that it isn't much use implementing OCR for this because most of the street Cantonese you see online never use the assigned characters. There has never been any standardisation for it so people can choose whether or not to use the debatable "proper" characters which people use in gossip magazines or certain newspapers in Hong Kong. For example, 哥 for 嗰, D for 啲 and the radicals are usually dropped, like 甘 for 咁/噉, 吾 for 唔 訓 for 瞓. Basically, If you don't know the language it wouldn't be much help anyway since the dictionary definition won't match the context. Besides, we don't even have a Cantonese dictionary yet so there's really no point scanning it for now.