"The URL for each article must contain a unique number consisting of at least three digits. For example, we can't crawl an article with this URL: http://www.google.com/news/article23.html. We can, however, crawl an article with this URL: http://www.google.com/news/article234.html. "
(Source: https://support.google.com/news/publisher/answer/68323?hl=en)
That's because your excerpt from Google News' guidelines left off a very important addendum: "Please note that this rule is waived with News sitemaps."
Thought these days a news sitemap suffices.
I would personally still add the 3+ digit unique number to the permalinks and eventually if necessary remove it once rankings improve overall on Google News.
Some Back Story
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I consulted for a Movie News and Review website for about 6 years. We had news sitemaps and would show up on Google News once in a while, but one of the small yet significant changes that we made that increased ranking on Google News was when we implemented adding a unique number to urls.
That was implemented back around 2009-2010.
We stopped using that unique numbers in the URL around 2013, mostly because the numbers were becoming pretty darn big. We noticed a small downtrend in Google News traffic which stabilized in a couple of months.
For anyone using Wordpress unique numbers can be added using a permalink structure such as:
/%postname%-%post_id%/
also it makes the URL longer, less user friendly and you have to deal with an URL migration that you might have to revert at some point (i.e.: the example you mentioned)
additionally: as it is mentioned that the 3 digit requirement is "waived" with a google news sitemap it is a strong indicator that this is a crawling, not a ranking directive.
my 2 cents: don't do it, as it would be a clear violation of the golden URL rule a.k.a. "Don't overdo the f###### URLs!"
"Please note that this rule is waived with News sitemaps."
so basically the >= three digits rule doesn't apply any more (for years now), as a matter of fact i don't know why google still has in in there as it always leads to a lot of confusions.
i once consulted a big newspaper which were in an ongoing project to change their URLs just because one of their (middle)managers has read this spec...