Each to there own, I guess that's the individual judgement thing...in the end if you re comfortable portraying or writing opposite non historic but deceased real person then all is good.
I understand the Diana thing and won't argue against it ( I could) so in that respect if a co writer objected , I would re visit writing for her. As for Paul Walker
, again I understand where you are coming from , he left a body of work that will provide enjoyment for so many for many years to come and while , like you I wouldn't wish to write for him so soon after his passing, so many people associate Paul with Brian that portraying his characters (particularly that one) would be difficult for me .....
I guess ultimately the judgement as has been said ..is yours as the writer