The following sequence occurred on Server Fault:
A question with gibberish was posted by a new user, and I flagged as rude or abusive as soon as saw it in line with What makes something rude or abusive and when should I flag it?. Based on past experience of flagging posts from new users containing gibberish are a prelude to the post being edited to contain SPAM.
The question title was edited to have a SPAM phone number.
A different new user posted a gibberish answer, and I flagged as rude or abusive as soon as saw it.
The question and answer had numerous comments posted containing a SPAM phone number.
Since the SPAM wasn't in the body of the question or answer, think there were no auto-flags from SmokeDetector which is why the question seemed to last longer before being deleted.
The question remained for more than 15 minutes (All must wait 15 minutes after asking to accept any answer), after which the SPAM answer was accepted.
At this point the poster of the SPAM answer has got 16 reputation points and evaded the limits and restrictions for new users.
Some of the SPAM phone number comments on the question got upvoted. According to this comment on What are the reputation requirements for privileges on sites, and how do they differ per site?:
Upvoting comments shares the rep requirement with post flagging, so at the moment, it's 15 rep.
Therefore, assume the upvotes on the SPAM comments came from the spammer who had their answer accepted.
About 20 minutes after the question was asked, the question got deleted.
The deletion of the question then reset the reputation of that of the user answering back to 1 and there re-applied the new user restrictions.
To help avoid a pair of spammers or trolls who work together to evade new user restrictions, would be possible to prevent an answer with pending SPAM or rude or abusive flags from being accepted?
The above was my suggested fix when created this question.
As pointed out in comments, unscrupulous answerers or trolls could abuse the fix by flagging to prevent acceptance of a valid answer. I'm not sure how long before a moderator would decline a flag from an unscrupulous answerer or troll, and flag ban them to stop further occurrences. Apparently there's no tool to issue manual flag bans.
I now prefer the following which was provided in a comment:
Alternatively, delay only the reputation gain from acceptance until the red flags are resolved (and remember that no reputation is given to deleted answers). This idea would make wrong red flags less disruptive and confusing (since we're not telling the asker that the answer has a flag on it and they need to come back later to accept). – Laurel