Usage of all caps has absolutely nothing to do with language. There are plenty and I mean plenty here who's first language is not English ranging from Japanese, Chinese, multiple Spanish speakers, Russian, etc and they did not just suddenly type a message IN ALL CAPS for no reason. Translation programs don't use all caps either, if anything they forget to add capitalization period.
Back when people first started typing and even now there are people who will type a quick message in all caps due to their typing speed and not catch it but as I already said "After your first sentence you should have realized it was on" and that still stands true. Which mean it was either a conscious act to use all caps or a lack of damn to turn it off even after it was apparent.
Didn't ask for him to use correct capitalization and punctuation so chill with the bullshit, this isn't a damn English test. But purposely writing a whole message in all caps, is just annoying.