Those should of course be reported to the police, since threatening in this way is illegal. I quite understand that you may not feel able, but this is criminal behaviour that the police should rush to deal with with the same enthusiasm they rush to arrest women for tying suffragette ribbons to trees.
Absolutely. These kinds of messages and tweets should be reported to the police. If a mere ribbon is sufficient cause for the police to come knocking on the doors of women, they can bloody well do their job and investigate the kind of crap women receive regularly.