While that is a confusion-clearing thing to do, my understanding is “who” is used in reference to people, and “that” refers to things. So, grammatically incorrect but semantically correct.
In this case, I think adding an article would also have cleared the garden path— that is, “The Doctor Who […]” — but yeah, the meaning is clear enough this way.
Edited the title to say “doctor that” instead now
I appreciate your attention to detail. Have an updoot.
While that is a confusion-clearing thing to do, my understanding is “who” is used in reference to people, and “that” refers to things. So, grammatically incorrect but semantically correct.
Grammar rules exist to make communication clearer. If they’re getting in the way of that, ignoring them is usually fine.
In this case, I think adding an article would also have cleared the garden path— that is, “The Doctor Who […]” — but yeah, the meaning is clear enough this way.
“Doctor, Who Said…”