I do understand your point of view. But limiting the writer because of possible triggers for some people is not good.
Since the book had a warning and from the beginning we see that it is not just little blood but gore and MC getting scared and all, even scene with fish in first book. You had an option, and if you chose the last one, you had a huge warning of upcomong gore and scenes on the way. So on authors side, he did everything to warn you.
And yeah, for some, something may remind them something hurtful and trigger them, but that doesnt mean that we will start cutting the scenes out. There are a lot of movies and books with even more, still they hit top selles and all.
And i am really sorry about your situation, but becuse you are triggered, it doesnt mean that the author will take down something involving a car crash. Someone may have experience plane crash or his loved one.
Everyone of us have some triggers and author not anyone else can predict it or know, so they only option is to creat what they want to create and leave it for people who are not triggered or can handle it.
And guys! Someone who cant handle the scene or starts hahing flashbacks or something should put the book away. It is clear that not every book or movie or whatever is made for everyone.