I wouldn't call that a threat, that sounds like a regular Tuesday after receiving some scam messages to boost my socials, get followers or the typical commission scams.
Personally, I would always remind the following:
Paying for "promotion" is meaningless, why?
If you want your content to be out there and reach more people is simply having several social media accounts and share on the communal spaces of that socials (Like discord servers or facebook groups), but despite if you pay or put on your own the content in a new place, is up to the people to actually click on your content.
Then there are the ones that sell you "followers" and "engagement" but we already know that these are bots, they are not real people and in most webcomic platforms to use these bots is actually illegal, is easy to notice mostly when nowadays a series reaches ad rev so easily but when you see the series it has views, not many followers, a random number of likes but almost no comments. Then if the staff gets suspicious at the point of checking the activity of your series and the irregular growth they may block your account and delete your series.
Most of the time I find kind of stupid these people because first is not a service you have been looking for and they can apply for. Attempting to insult you or whatever just exposes even more how fake they are.