This has been suggested before, but denied for, as I recall, the reason that it could encourage people to make fake Scammer accusations to make people have bad records.

Now, the common counter argument is that a user could go on a scamming spree and people wouldn't know during it, however, if multiple people are accusing a user of scamming but there is not enough proof to lock yet, they do take a close look and perform anti-scam spree measures if need be.