Counsel, Canada’s Criminal Code specifically prohibits child sex tourism since May 26, 1997. Many other countries have passed similar child sex tourism laws. Nothing in principle stops any US state from criminalizing abortion tourism.Delightful.
The only way it can work in criminal law theory is if they criminalize "communicating for the purpose of obtaining an abortion" and deem the communication to have occurred in MO. I don't think they can even do it as a "criminal conspiracy" charge because that involves agreeing to participate in a criminal act and abortion in Illinois is not a criminal act.
See also https://en.wikipedia.org/wiki/Child_sex_tourism#Extraterritorial_jurisdiction