Hm, that's close but not, I think, quite right. In the scene with the blind girl Arthur tries to insist on helping her (which she refuses) & also seems (in a number of monologue-like comments) worried about her safety. But there's also a very disconcerting moment where there's a high-angled shot that comes out of the blue where he suddenly bursts out (to himself--she's too far away to hear, & it may be just a fantasy moment, stepping outside the frame) that he'd like to tear her knickers off.
Arthur clearly is not "really" responsible for the rape and murder; the tramp is. Yet his momentary fantasy seems to be one of the moments of strange entanglement between their fates. When the girl is raped the knickers are indeed torn off; this is not reported in the paper, yet Arthur accidentally mentions the detail to his wife, which is what sets off the train of investigation that lands him on the gallows. Is this just because he's perpetually confusing his fantasies with what happened? Or does he have some uncanny knowledge of the rape? As we know, Arthur & the accordionist are weirdly entangled throughout the film (just as the blind girl & Eileen are): characters sometimes momentarily confuse them, & their actions & fates seem entwined.
My own take on this (though many interpretations are possible): the tramp has not up to this point seemed anything but a little pathetic & bewildered; & indeed later on he seems completely bewildered that he's done such a horrible thing (& even more bewildered when he encounters Eileen & confuses her with the blind girl). Perhaps then the eerie, disconnected shot of Arthur wishing to tear the girl's knickers off is a moment of eerie transference, a desire transmitted (call it ESP or whatever) to the tramp, who actually fulfills it, even, perhaps, against his will.
And rememeber that scene where Joan hears the accordian man and later tells Arthur that she thougt it was him.
Sometimes it is best not to try to analyse Potter, and just go with the flow.
A bit like watching a David Lynch film.