I've just learned that this is an RC-critical bug according to §9.1.1 of the Debian policy, which states:
"The location of all files and directories must comply with the Filesystem Hierarchy Standard (FHS), version 2.3". FHS 2.3 states in §4 "The /usr/share hierarchy is for all read-only architecture independent data files". Therefore, bumping this to severity: serious.
signature.asc
Description: OpenPGP digital signature