Rather than simply going "you're on your own mate", the suggestion that seems to be causing so much offence is that a government which expects the international community to provide them with military assistance for the security of their country's people should, in return, be expected to respect and adhere to the laws and limits of the international community.
There are very real grounds to consider that is not the case, and indeed that it is not a particularly fringe viewpoint within the government, wider political and military bodies and the voting population that there should continue to be an expectation of supplies being provided without an accompanying expectation of adhering to those laws and limits.
Supporting the unconditional supply of military equipment that is used in Palestine is effectively supporting the use of such equipment in the killing of Palestinians and the destruction of Palestinian society. It is saying that those very real deaths and harms are an acceptable price to pay, in their eyes, to reduce the risk of deaths and harms in a different population.
That might feel distasteful to some people, to have to think about their own acceptance of that and what it means about how they weigh up the values of the lives in the balance. So it gets equivocated and deflected and denied.