Is risk of necrosis too high with the scar tissue in my nose tip? (photo)

Usually, if there's scar tissue in the tip, that means there's been previous surgery. Did you already have a rhinoplasty?Carving excess scar tissue out of the tip isn't something that should cause necrosis, unless it's done too aggressively. How good of a candidate you are for revision (or a primary) depends so much on what your nose looks like now. Photos would sure help. Photos would allow for morphs.
In fact, I'd love for you to see some excellent professionally-designed morphs of what could possibly be done with your nose. Morphs could also help you identify what's bothering you, and help you set a goal for the rhinoplasty that's accurate for your tastes.  (Side note: in my opinion, morphs should always be done by the surgeon, or he should direct an assistant as she makes the morphs. Morphs should be made with a constant eye to what actually *can* be done in surgery, for that particular nose, and only the surgeon has that information and judgment. Another aside: I also recommend that you not show morphs made by one surgeon to a different surgeon. If a surgeon makes his *own* morphs, you get to see whether he understands the important issues of your nose, and how your nose should be changed. But if you show the surgeon someone else's morphs, and he says "Of course I can make your nose look like that," then you don't really know if he fully understands, or even recognizes, the important changes shown in those morphs. And you don't know if he can make those changes during surgery.)
Remember also that rhinoplasty is an exquisitely difficult operation to get right, and you should only have surgery if you are able to make yourself very confident in your surgeon's skills. The changes that a revision nose needs require advanced techniques, and skill that most plastic surgeons don't possess with expertise. For most noses, it's much better to not have surgery than to have inexpertly-performed surgery. Read my essay on how to stay out of trouble while selecting a rhinoplasty surgeon. And for those who have had previous surgery, it also discusses how to tell whether your first surgeon should be performing your revision. And it also discusses how to take photos that are best for online evaluations.
Your nose is also a perfect example of why computer imaging is mandatory in rhinoplasty. You need to know exactly what the surgeon is planning to accomplish -- what features he thinks he can change, and by how much he thinks he can change them. I always email morphs to my online rhinoplasty consultations. When you see the surgeon's goals in the morphs, you'll know whether he has an eye for an attractive nose, and whether he shares your opinion of what constitutes an attractive nose. You'll also know whether the changes he proposes are large enough to be meaningful to you, and whether he understands your wishes enough to address all of your priorities. How would you ever get that figured out without the morphs?

In the hands of a rhinoplasty specialist, skin necrosis is extremely rare. We have performed revision rhinoplasty on many patients who had multiple rhinoplasty surgeries previously with no issues like that. While an exam is necessary to know for sure, you should be able to have your bump taken down and your nose made straighter.

Unless you had multiple previous rhinoplasty I don’t see the risk of skin necrosis being an issue. Perhaps the surgeon you sent to doesn’t do many noses. Get a few other opinions.