Agreed, "Great Scott" is a thing long before Scott started making any products.
This has probably been posted but I dont have time to read all 7 pages.
WIKIPEDIA
The expression is of uncertain origin. It is believed to date back at least as far as the American Civil War, and may refer to the commander‑in‑chief of the U.S. Army, General Winfield Scott. The general, known to his troops as Old Fuss and Feathers, weighed 300 pounds (21 stone or 136 kg) in his later years and was too fat to ride a horse.[1] A May 1861 edition of the New York Times carried the sentence:
These gathering hosts of loyal freemen, under the command of the great SCOTT.
In an 1871 issue of Galaxy magazine, there is:
"Great—Scott!" he gasped in his stupefaction, using the name of the then commander-in-chief for an oath, as officers sometimes did in those days.
The phrase also appears in the 3 May 1864 diary entry by Private Robert Knox Sneden (later published as Eye of the Storm: a Civil War Odyssey):
‘Great Scott,’ who would have thought that this would be the destiny of the Union Volunteer in 1861–2 while marching down Broadway to the tune of ‘John Brown’s Body’.[1]
Another possible origin is people seeking to emulate the German Prince Albert of Saxe-Coburg and Gotha altered and anglicized "Grüß Gott!", or "God bless!" into "Great Scott!". The etymologist and author John Ciardi once believed this, but later recanted in a radio broadcast in 1985. Despite that recantation, the expression is likely to be a minced oath: a mild substitute for invoking the name of God; very possibly derived from the phrase "[by the] grace of God".
Scott USA clearly has no case.
If I was ON3P I would not worry about it a bit. They are not going to spend the money to sue you. It is free to send someone a letter from a lawyer, it costs a lot to try take someone to court.