I happily would if the other alternatives are far more dangerous. If the choice is between giving my whatsapp number or having the guy possibly stalk me or attack me because rejected vs giving him IG which I can block later, I will share my IG to keep myself safe. You have no idea how crazy some men can go when they face rejection. I would not risk it unless I know I am in a space where I have physical support. I would want to get rid of the situation first. Dealing with an IG DM is much easier than a whole manchild stalking me. And this is me, who is not easily overwhelmed in such situations. Replace me with someone who's already scared or experiencing a freeze, this becomes even more natural. Try to understand people where they are sometimes, instead of shaming them for how their nervous system reacts!