I’d never heard the rub on gums method. People I knew gave a *small* amount in the bottle diluted with water or, more commonly, straight in a pacifier.
I’m certainly not defending the mother, but some of these seemingly odd practices have been around for generations without sending the kids to the hospital. Apparently some generations had more common sense.
My brother is 52 and I remember my grandmother rubbing whiskey on his gums and putting a very small amount in his bottle when teething. My grandfather was a Pentecostal pastor but they kept a small bottle of whiskey in the house for ‘medicinal’ purposes. She also would give it to me with honey and lemon when I had a cold.