Ambiguous grammar intrigues me; I hope I can be forgiven a minor hijack.
Assume, of course, no prior knowledge of PhillyGuy: View the sentence in isolation.
When I first read his sentence, I assumed PhillyGuy thought she was guilty. Why? The use of “but” to adjoin two clauses usually implies that the second clause is in contradiction to the first. (But in fact “but” was just thrown in for emphasis.) Moreover the initial “As for” focuses the intended meaning onto “guilt.”
OTOH, more careful reading leads to the opposite conclusion. The ambiguity is whether “it” refers to “guilt” or to “presumption”. But a presumption can be “strong” or weak, while guilt tends to be a simple yes/no thing.
The moral of the story: Take a few seconds for a reread before posting. Ambiguities which wouldn’t arise face-to-face can wander into the written language.