"Worth their gold", "worth its gold" - are these expressions idiomatic?

The question stems from this question on Literature.SE and the discussion that followed.

History:

The poem "Confessions of a Born Spectator" by Ogden Nash (allegedly) contains a line "Buy tickets worth their radium" (see the full poem here, for example).

It turns out that the line is misquoted pretty much all over the internet and the actual line is "Buy tickets worth their weight in radium" as @user14111 pointed out in his answer.

However, before his answer appeared, I was "explaining" (rather arrogantly) to the topic starter that:
'The expression "worth their weight in gold" (and similar) is sometimes abbreviated to "worth their gold".'

I'm not a native English speaker and my assumption that such an abbreviated version existed was based on a number of Google hits that I got for "worth its gold"/"worth their gold" (full phrase search). Examples: 1, 2, 3, 4, 5, 6 (I could go on).

Question:

Is such an expression idiomatic in English? If yes, what does it actually mean?

No it's not idiomatic. It sounds like you owe them an apology.

You might be confusing it with "worth their salt", which means someone who is competent.

Eg "Any doctor worth their salt would have recommended a head CT scan"

Those examples you cited are all plays on words - that is, they are a humourous variation on the phrase "worth their salt", because the subjects of the articles have something to do with gold - winning a "Gold Award" (1), a gold-panning holiday (2), or gold smugglers (4). I can't see the connection for number 3, maybe that is simply someone making the same mistake as you.

Outside the context of a play on words, it doesn't work.