actually looks like you are just bringing up a story which was in the media lately and which was a complete hoax (a PsyOp) exactly  with the aim to crack down on free speech:
https://steemit.com/news/@lavater/michelle-carter-case-is-fake-news-hoax-psyop-freemasonic-attack-on-1st-amendment
words cannot kill a person. serious mental health issues can.
if a girlfriend tells me to kill myself why should I do it? I would send her packing.
in any case it was an absurdist case to start cracking down on the 1st amendment, the truth is hateful for them and thats what ultimately they want to ban.
it was all laid out by David Cameron at the UN. see what they consider as "hate"?
https://youtu.be/aeNVoozb0KE

Body language and looks can have an influence on people's minds. If someone sends a picture to someone else then it can influence their mind. Should the picture be considered contraband and the sender punished if the receiver does something irrational?

If the answer is no then why are words different from photos?  If we follow the logic consistently then a picture, body language, even micro expressions like emojis are speech which can influence minds. Memes are in any form which can contain information, so to police memes is going to be very difficult and to police memes only in text form is unfair.