Perhaps literalism? Although it's perhaps most frequently used in religious contexts (e.g., interpretation of sacred texts), it seems to apply here:
The disposition or tendency to accept a text, statement, etc., literally; the result of this, the interpretation of words in their literal sense. Occas. also: an instance of this.
Literal translation; this as a principle; (also) a peculiarity of expression due to this.
(both from the OED).
I think the second use applies particularly in this case: words that might typically register as euphemisms but are intended literally could be considered a "peculiarity of expression."