Remember the efficient market hypothesis of wishes. Aside from the body, are those a) likely to be the most effective use of the wishes, b) likely to be something the namekians haven't done (or consciously decided not to do) yet, and c) can the dragon do it? Like, they've had potentially over a thousand wishes since the death of earth. It seems likely to me that most possible forms of defense are already in place and insufficient.
I'm thinking of wishes like, say...
1) "Contact Toru and bring him to New Namek to coordinate with us."
2) "Contact Androids 17 and 18 and bring
them to New Namek to coordinate with us."
3) "Summon all the Namekian warriors to New Namek
now, instead of waiting for Guru to find out there's a threat and summon them the hard way."
4) "Give us a detailed report of what you know about the forces threatening New Namek"
Some of these might not work (in particular, the dragon probably can't summon powerful beings who resist, and wishes (1) and (2) might result in people choosing to resist a summons. But they're all wishes that are
in broad within the dragon's power to grant, and which would help us deal with the immediate crises we face. And which the Namekians themselves could not have made
in advance because they didn't know they needed to make them.
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*(can you ask the dragon for information? They seem very knowledgeable and would almost have to be, in order to carry out some of the wishes we've seen)