I'd sooner trust a carbon disc fork provided it's designed for the purpose.

Steel will have to be built like a tank and just as heavy, or it will flex by the caliper mount at the dropout, and bad things can happen. I had a steel disc fork without flex problems, but it was absolutely tank-like.

My CF disc fork is tank-like for CF, which means it has big burly legs that shrug off those forces, is easily as heavy as any alloy fork, yet manages to come in lighter than the steel one. ZERO flex, and not a sign of flinching in 3 years.