When I run dumpRdf on the wiki with WikibaseLexeme enabled, it generates some rudimentary data on the Lexeme (see below) even though I have disabledRdfExportEntityTypes setting set to not export lexemes.
The script should take the setting into account, same as the RDF export through Special:EntityData already does.
The excerpt of the RDF dump related to lexeme lemma data (this is the only information being exported, and note: This is not a final implementation or RDF mapping, this is more of the proof of concept code which generates it)
wd:L2 a wikibase:Lexeme ; rdfs:label "apple"@en ; skos:prefLabel "apple"@en ; schema:name "apple"@en ;