I agree that trans people collectively are not responsible for this - I have trans friends who are utterly horrified by what is being done supposedly in their name. I also believe one of the speakers at the event being threatened is a transwomen.
However, transactivism (or whatever you want to call this current movement) promotes violence against women. Threats of murder, violence and rape are routinely used (see terfisaslur.com/). Women have been attacked for attending meetings. This has been supported by transactivists and their organisations, with further violence being called for (e.g. Action for Trans Health "we must be radically and transformatively violent"). Then you get the threats to burn down venues hosting women's meetings (with the women inside them). Masked men blocking women trying to attend a meeting () I could go on and on with examples and I'm sure many others on here could.
It's telling that when a transactivist held a 'trans culture' event in a library, the 'culture' involved baseball bats and bloodied t-shirts glorifying violence against women: www.mumsnet.com/Talk/womens_rights/3232446-San-Francisco-Library-promoting-VAW-in-the-name-of-trans-culture
Now, I don't think this represents trans people generally - and it's not something that represents the transsexuals that have been part of my (LGBT) community for years - but this is a new, frightening movement based around extreme misogyny and violence towards women.