UK surgeon Nick Maynard, a volunteer at Nasser Hospital, tells Good Morning Britain that he and other doctors tried to bring baby formula into Gaza and the Israelis confiscated it from them with no justification. [0]
Without a justification the decision is arbitrary and silences any ability to push back against it within the normal bounds of dialog. A justification would potentially allow aid groups to remedy whatever the specific deficiency is if it is a reasonable deficiency to remedy.
If there was a justification it might be acceptable - depending on the justification - without a justification it is unacceptable when there is such a clear need. The aid is blocked and there is no recourse to unblock it outside the current attempts to just smuggle it in.
I think in this particular case it's quite safe to say that those blocking the shipments aren't acting in good faith, however.
The main ingredient in Hamas' rocket fuel is sugar. https://en.m.wikipedia.org/wiki/Rocket_candy
That would be an acceptable justification for confiscating sugar. If Hamas were making rocket fuel somehow out of baby formula, then yes, that would be an acceptable justification.
That said baby formula cannot in fact be meaningfully used to make explosives, so this is not acceptable.
If you can get your hand om 20kg of oxidiser that is. It is all more than ridiculous.
Edit: and Nick Maynard is a national treasure.
Only solution is to cut off all wells and water supplies.