Building a medium-like site for content marketers. How do i prevent any subdomain from affecting my main domain ?

hi

so im building a content management tools for SEO professionals & content marketeers. You can manage your SEO writing projects there and directly publish to wordpress, medium, etc. kill the word file i say!

now, the way im building it is each content marketeer/seo professional gets a subdomain. and that is where they manage everything. they can create links to their content and share it with their clients, etc.

Here comes the problem.

I dont want any of this to affect root domaun . like I dont want my corporate email or my corporate website or anything to be affected. Ever.

Now, i could choose to stop the individual subdomain even being indexed. its kind of an internal page for content marketers...so i could block crawlers entirely ? sure. but content marketers & SEO professionals also want to test out their theories - where do they do that today ? instead they can create a dummy project and potentially test out everything. even dangerous SEO strategies. Kind of like imgur for SEO, if u will.

so we are talking content marketers here. dangerous lot. i fully anticipate getting takedown notices. what do i do to make sure my main domain is guarded ? ive been wondering about medium.com . they do a great job of this right ?

any advice would be super helpful!