Actually this is pretty well known and if you look at other actors who were in the movies that played any adult role you will find that a lot were threatened to take the roles in the same way.
As crazy as it seems now, back then it was a bit of a gamble, making a movie from what was ostensibly children's fantasy novels, no matter how wildly popular. There was a history of flops, such as the Chronicles of Narnia films which were so bad CS Lewis' heirs said they never wanted another live adaptation made.
https://m.youtube.com/watch?v=ItM8J1o_ZnM