Such contracts and associated surety bonds are similar to indentured servitude or serfdom
Ha ha, quite liked that line on Wikipedia. Yes, indeed, good companies shouldn't need it, and it surpresses the equilibrium level of pay. Worse is to bond already rated pilots. Quite why we put up with it, I don't know. It's relatively unusual in other professions.
But as mentioned above, if there's any doubt, there's no doubt - don't go - it's one hell of a big move, and you or the family being unhappy there can be very detrimental. They might not be able to grab you in Europe, but what if you're rostered with a ME layover? I knew a very unpleasant character who did a runner from Singapore with a load of their money, and apparently he squirmed like hell when he had a surprise rostered trip through SIN.