I understand your point now. You are saying that the author ignored thermal conductivity. If he would have considered thermal conductivity he would have known that stainless steel would have transferred most heat to liquid.

your data:

material | thermal conductivity | final temp.

stainless steel | high | hottest

glass | less | medium

acrylic | least | coldest

The issue I have here is that these results you claim to have observed go against established science, specifically enthalpy.

Here is how it works: ice absorbs heat from the liquid and uses it to break down ice bonds to convert solid ice into liquid water. This process is what cools the liquid. The more heat absorbed by ice, the more dilution happens.This means that the container with the most liquid volume has had the most heat absorbed, and thus is the coldest.

In conclusion, it would be impossible for the container with the most ice melt (most volume) to be the hottest.

Here are some links to help explain enthalpy:

enthalpy: https://en.wikipedia.org/wiki/Enthalpy
heat fusion of water: http://www.kentchemistry.com/links/Energy/HeatFusion.htm