Some Qur'anic passages take the form of a question and response even though identifying a particular person who actually asked that question is not required. Presenting a possible objection and then answering it is an established rhetorical method.
This form clarifies difficult issues, resolves anticipated misunderstanding and moves an argument forward. A hypothetical question has a different evidentiary status from a historically attested question that occasioned revelation.
The presence of dialogue therefore does not license the interpreter to invent a specific meeting or questioner. The rhetorical role of the exchange must be considered first.