It changes nothing.
MN has been linking to FB for a long time. People have been posting threads to FB for a long time. If anyone likes the thread it appears on their wall but it does not identify you in anyway.
And the main point...everything you write here is already on the internet for the entire universe to read.
There is an FB like button on everything now. Everywhere you look online. If you don't like it, don't click it and your life will go on exactly the same as before.
The foot stamping and moaning about a minor insignificant change is really getting tedious.