If these fonts *do* work for people with dyslexia, it’s a reasonable guess that it might be because their severely distorted letterforms, compared to regular typefaces, disrupts normal word-level shape recognition and forces a similar engagement with letter-by-letter word recognition that seeing words in all caps does.
The problem is that if that hypothesis is correct, it also probably means that the dyslexia typefaces will get less effective for a dyslexic person the more they read with it.