First, The HMIS reactivity rating is obsolete. It was replaced with "Physical Hazard" around 2002. All you needed to get a reactivity rating of 0 is to not violently decompose, and not react with water (releasing energy) even at eleveted (fire) temperatures. Butyls typically show up in the Health category. That's probably the reason Hot Knife has a health rating of 1.
Oh, and ask Steve Smith. He will emphatically tell you they are NOT the same! I have tried both, and I and others find Hot knife slightly better on the nasties. Not to say Blaze is bad, I have used it on normal soiling with good results.