The picture's from OP's post are neither from the correct platform (456 Platform is pictured, not the J/Z) nor (as far as I can tell) are they of the suspected assailant. Additionally, the description of the suspect from this post is completely unrelated to what the linked articles even say... I've included the ACTUAL information from the articles below:
"Described as white and in his 40s with blonde hair and was last seen wearing a brown hooded sweatshirt and blue jeans" -Daily News
"A man was stabbed to death by a blonde-haired stranger...in his 40s" - NY Post
"Authorities are working to see if there are surveillance cameras that may have recorded him." - CBS