If they do that, then they're definitely harming any customers who have a position they need to get out of, as opposed to only potentially harming them.
If you believe that the platform is so broken that it shouldn't be used (and I'm not arguing against that, btw) then a more reasonable solution would be to only allow position-reducing trades. That would also reduce overall trading volume on their platform.
Not that I expect them to do any of this, just pointing out that 'shut everything down' is not necessarily the best approach.