If think the sender can force an arbitrary latency in decoding with a signal with noise added but i might be wrong. If the MITM sends a signal before the measurement is complete (ccertainty that the noise is leaning one way is above threshold) he either produces unlikely signals (detectable, since all the information is sent after the decode, htus the signals entropy will vay with time n a stair step way) or he occasionally transmits a wrong signal.