Magnetars are highly-magnetized (ca. 1016 G) neutron stars which may randomly emit bursts of high energy radiation, in the form of hard X-rays or much more rarely giant flares of gamma-rays during their active phase. Recent observations of GRB 200415A, a short and very bright pulse of gamma-rays, have been claimed to be an extragalactic magnetar giant flare (MGF) whose host galaxy is the Sculptur Galaxy (NGC 253). However, as the redshift of the transient object was not able to be measured, it is possible that the measured location of the transient on the celestial sphere and the location of the local galaxy merely coincide. Thus, its real progenitor could have been arbitrarily far away, leaving the standard model of short gamma-ray bursts (SGRBs), the merger of two compact objects, as an explanation for the observations. In this talk, I will present an estimate of the false-alarm rate of SGRBs being incorrectly identified as MGFs using population synthesis to simulate data collected by the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope.