The Bose-Einstein correlations of photons emitted from a longitudinally expanding system of excited matter produced in ultrarelativistic heavy ion collisions are studied. Two effects found in recent calculations-that the correlation function in longitudinal direction exhibits oscillations, and that it takes values below unity-are demonstrated to be numerical artefacts and/or the results of inappropriate approximations. Thus, the general quantum statistical bounds for the two particle correlation function of a chaotic source with Gaussian fluctuations are confirmed. Two different expressions for the two-photon inclusive distribution are considered. Depending on which of the two expressions is used in the calculation, the width of the correlation function may vary by as much as 30%.