How is that twee?
But I can see where the twee is coming from. Even though it's not the word I'd use.
I am an immigrant. There have been times I have felt vulnerable becuase I stood out like a sore thumb. Some unknown internet random accompanying me would be an additional risk factor becuase the contact would be based on me informing them of my feelings of vulnerbility, my barriers being down in their company, a declared dependency on them and my revelation that I had lack of an available, known support system.
The idea is full of obvious security holes and has the potential to create greater risk.
As a concept it has the potential to allow rascist extremists to create a clean profile, let the campaign identify those individuals who feel vulnerable, gain close quarter access to them in a context of dependancy and make a statement through violence that is bound to generate media attention becuase of the connection to an known interet campaign backfiring.
Equally somebody radicalised, but as yet without a plan, is offered an opportunity of a "barriers down, even forced down should instincts set off alarm bells" random victim on a plate, that would generate a degree of backlash unthinkable had the victim been truely random rather than part of a high profile attempt to show solidarity.
And that is before you consider your common or garden sex pest who would happily have potential victims lined up declaring their vulnerability/barriers down status which blunt their ability to react despite any instincts that end up screaming " danger danger".
Which is why I think few people will paritcipate. Thus it becomes one more self congratualatory, attention seeking "activisim by click" act where the greatest gain is allowing people to feel good about themselves via the huge effort of using a social media hashtag.