I have as much sympathy for them as I would a drunk Russian who decides to piss on an electric fence (side note: Yes, those YouTube videos are hilarious).
It's a "damned if you do, damned if you don't" situation.
They accept a surrender? There's a chance they would explode, killing them.
They just shoot the surrendering Palestinian fighters? War crime, but they don't, ya know, probably get exploded.
That's tragic about the hostages. :( But, it makes you wonder if this is another "surrendering WW2 Japanese soldier" problem that caused them to adopt this rule of engagement.