"Admittedly bad"? Admitted by whom? Perhaps if judging by today's standards one could consider them poor, but the optical effects in The Birds were state of the art in 1963. The sodium vapor ("yellow screen") process was used for some effects shots because it minimized or eliminated the fringing...
Don't you just love (not!) all of the wild theories that get written (or spoken in commentaries by a some scholar) about movies. Makes me think also of preachers who will create a whole sermon based on a reading of a Bible verse that has absolutely nothing to do with actual meanings of the words...