That’s not correct. It’s the high ketones that are the danger. It’s possible to get ketoacidosis with normal blood sugar - euglycaemic ketoacidosis. Here’s one of many articles:
Summary Euglycemic diabetic ketoacidosis (EDKA) is a clinical triad comprising increased anion gap metabolic acidosis, ketonemia or ketonuria and normal blood glucose levels <200 mg/dL. This condition is a diagnostic challenge as euglycemia masquerades the underlying diabetic ketoacidosis. Thus...
edm.bioscientifica.com
People without diabetes can also get ketoacidosis on rare occasions and their blood sugar is normal. As ketoacidosis can sometimes be connected to certain medication that a number of people with diabetes are on, saying that it’s somehow ok just because your blood sugar is normal is potentially dangerous.
High ketones are a concern whatever one’s blood sugar.