It also depends what someone considers "suicidal" to mean. People have different understandings of the word and different experiences that influence their beliefs or, in many cases, naive assumptions. If someone dreams about and longs to commit suicide and thinks about it and plans for it every day, are they only suicidal once they attempt? Are they less suicidal than someone who has one random thought and spontaneously attempts, with or without the intention of actually committing suicide? What if they know they're not quite ready but know they want to do it at some point? As many have expressed, there are a lot of reasonable explanations for fear, including unavoidable biological forces. Imo, you can be suicidal even if you don't know if you'll ever do it.
Some people just feel the need to put others in boxes or assign labels either for their own security, because they need to contextualize what they don't understand/can't handle, out of pure ignorance or for many other reasons, some of which are ultimately selfish. But it says so much more about the person who makes the comment than the person who may be scared or hesitant to attempt.
Another one of my "favorites" is that a failed attempt is "just a cry for help." It's maddening on so many levels. A genuinely great person whom I deeply respect once said that to me (not about me), and I was blown away; it has bothered me for years, though it likely was just a thougtless remark, however off-base. I think perhaps people make blanket statements that are based on specific experiences or individual data points, so to speak, not recognizing that it's completely inappropriate and unreasonable to assign such judgments on a broader scale. Unfortunately, a lot of people make comments for the wrong reasons, even if their intentions are not malicious in nature. It is a shame because these declarations are entirely unnecessary and so hurtful.
To anyone who has been the recipient of such comments, I am sorry. They are unwarranted, misguided and unfair, to say the least. You are not alone, and no one else's distinction or classification is more relevant or important than how you feel.