Probably and guess are two different things
prob·a·bly adv.
Most likely; presumably.
adv 1: with considerable certainty; without much doubt
guess v. tr.
1. To predict (a result or an event) without sufficient information.
2. To assume, presume, or assert (a fact) without sufficient information.
Thanks for the vocab lesson, my opinion stands.
I do honor your position of defending these parents, I do not.