Bullshit. In a scientific setting, would you start your sentence as, "MRNA is the messenger RNA"? Somethings are purposefully stylized differently. mRNA, iPhone, io.js, etc. Naming conventions should be respected to aid clarity.
Science has multiple capitalization rules as well. mRNA is not a name, the same as genus and species are seldom capitalized. If you have a mRNA named Bob, then the name is capitalized.
