Status of Glk Z-Machine interpreters

MIT is compatible with GPL (both v2 and v3) so this is not an issue, an MIT-licensed interpreter can be plugged into anything where GPL would also work.

(Unlike e.g. Apache-2.0 which is infamously not compatible with GPLv2 - hence the popularity of MIT/Apache-2.0 dual licensing in some corners of the FOSS world.)