re: "This client just posted a job. I believe it was flagged inappropriate. Does that mean it is a scam?"
Often, yes, it means it's a scam.
But not always.
Sometimes jobs are NOT scams, but are nevertheless not allowed by current Upwork ToS. Upwork allows many types of jobs, but not all types of jobs.
A job might even be taken down because it is posted in any language other than a small handful of allowed job posting languages. There are lots of reasons a job might be taken down.
I have posted about 50 jobs.
A couple of them got flagged as inappropriate by automated filters and/or inexperienced Upwork operatives with limited English language ability. I had used wording that got caught in the filters. I changed the wording slightly, and was able to post the job and hire freelancers.
I can confirm that the job you are referring to has been removed from the marketplace and actions have been taken against the client's account. Please, stop communicating with them.