Sam2:
One is that it’s a Nes that involved the Hatzalah of Klal Yisrael, which necessitates Hallel Mid’rabannan (Gemara in Pesachim)
The second is that there is a Chiyuv (possibly Min HaTorah) to say Hallel for a Nes that leads to the Binyan Beis Hamikdash
Even if I were to accept the premise of these arguments, IMHO they raise more questions than they answer. Off the top of my head – Why can’t the same be said of the Yom Kippur War? And why would these arguments be applicable to any day besides 5 Iyar?