I am not privy to any "secret tactics," but common sense tells me that even in a bomb-on-board situation, there are quite good reasons for a fighter escort.
1) provide eyeballs on the plane in trouble: suppose the transponder signal (or COM transmission) disappears? Is it an explosion, or an electrical fault, or a reversion to a Plan B (attempted hijacking)? An escorting jet can see whether the plane is still there, or making hand signals, or has too many people in the cockpit. Radar can't.
1a) And, of course, take tragic-but-necessary action if the situation has fallen completely under unfriendly control - or literally out of control altogether.
2) provide asssistance in case of a non-catastrophic explosion (aircraft have survived bombings on occasion): Escorts can - inspect damage/leaks and report to flight crew - provide navigation help in case of instrument/NAV damage - relay messages - report situation in general to ground - request emergency response on landing if civilian crew cannot.
3) As to why fly for 4 additional hours to Tel Aviv? El Al is a special case (they have a - history - of being a prime target). And they have the strictest security on the planet.
Again, I have no clue as to their actual tactical options. But as a neutral observer, I'd imagine that Israel would really, really prefer that if there is even the possibility of a bad-actor on board, that (s)he be de-planed directly into their custody. Without "complications" from the laws, judges, extradition agreements, or politics of the other countries enroute.