I will say Stephen Hawking absolutely deserves it, one day, but I feel like the notable person should be dead for a certain period before we throw them on currency (certainly longer than a year). Conceptually I like the "50 year rule." Helps mitigate populism or overly politicizing it.
That results in the Queen (or King) being a remark on today, and the Scientist or other note-worthy contributor being a remark on our history (and values?).