@Charlotte196 was this through instant booking? Since you already ask for more information/better picture and he does not respond yet, my best suggestion is to send him another message with a deadline. "Hi X, I look forward to hearing back from you and seeing the updated profile picture by (put deadline here). Thanks!"
If it is an IB and you do not feel comfortable and the guest is not being cooperative, you have the rights to cancel. PLEASE keep in mind that the best way to do it is by reaching out to airbnb and ask for their help by explaining the situation and cancel from their end.