Your wording is actually not exact enough to delineate the problem: “it isnt a random result for God” might mean that God decided the outcome, so that from his point of view it wasn’t random, or that God wasn’t involved in the matter at all, so it was just a matter of human luck that Matthias got the job, and they screwed up properly.
To me, the first meaning is as plain as day. I started from the legitimate OT practice of casting lots (urim and thummin), and Proverbs 16:33 stating that though the result is random to the caster, every time the result is “from the Lord”.
The disciples followed that practice, following Peter’s sober suggestion, accompanied by prayer to the newly-ascended Jesus for a decision based on his knowledge of human hearts, and I argued that it follows that God determined the outcome of the lot in accordance with his purposes for the church, and in response to the simple entreaty of his church.
Glipsnort replied that that doesn’t follow - that neither we, not Luke, nor the disciples in the upper room, should presume that God would determine the outcome. God might well might simply have made his own random decision too.
In fact, he suggested, Luke might have made up the whole episode to make a theological point - presumably either a mistaken one that God did determine the lot according to his wisdom, or a more complicated one that disciples in upper rooms ought not to replace apostles by prayer, but should wait to be surprised by Saul on the Damascus road. Either way it would be the Bible lying for Jesus.
So the main dispute was, did God choose Matthias in response to the prayer and lots, or did he not care who got chosen, leave it to “ontological chance”, and not tell the disciples their prayer was misguided?