I think if Israel believes that weapons can be smuggled via sea, which is reasonable given the smuggling via Sinai and Rafah crossing, then they took the rational step of mitigation this risk.
That doesn't make sense, it seems as if they're held hostage by Israel forced to stay in the very land where their own terrorist government might impress them into servitude towards use against Israel.
The sad part is that Egypt has an obligation under international law to allow refugees into its territory. But Egypt refused.