Good points, Dave!
The THEORY (a Thermo-Bob reduces/inhibits/minimizes cylinder bore distortion) appears plausible; may be entirely valid. Yet, as you mention . . . corroborative data supporting the theory remains elusive. Anecdotes ("point estimates") may exist; the phenomenon may be universal. Availability of a statistically significant sample seems unlikely, to me.
That said, "Stands to reason," on the premise of positive Thermo-Bob implication regarding cylinder bore integrity, may be positive incentive (along with other factors) for Thermo-Bob installation .
“You better put down that gun. You got two ways to go, put it down or use it. Even if you tie me, you’re gonna be dead.” "John Russell" (Paul Newman), Hombre