It's a well crafted theory, yes, but still just a theory. For instance, there is an equally convincing theory that Charlotte suffered from childhood diabetes and wished to be able to eat sweets again.
The theory goes on to state that Charlotte later realized this was a dumbass wish to make and turned into, well... Charlotte. So in this case, Charlotte's being surrounded by candy but longing for cheese represents her having realized too late that she wasted her wish on something she didn't really want and lost her chance to obtain the thing she truly desired (presumably, to be cured of the disease entirely).
TL;DR It's just speculation, not legit.