shrimps will eat almost anything, lol
so yes i would say they would eat the holiday block, but i would recomend not feeding holiday blocks, they are mostly made from plaster and cloud up the water.
it would be better either feeding plenty before you go, and maybe get someone to visit your house and feed your fish when they can, or buy an automatic feeder, or even if your going away for only a few days, just leave them. lots of fish can survive easily for 3-5 days with out food.