The F1 paddock rumours suggested that the Mercedes reserve driver and Liam Lawson were the main choices to replace the American driver for the remaining nine races.
However, Williams opted against bringing in someone from outside their junior programme which has left the Sky Germany pundit scratching his head as to why.
Ralf Schumacher slams Williams for 'absurd' decision
The 25-year-old currently competes in the FIA World Endurance Championship with Alpine in the Hypercar category.
He has been looking for a way back into F1 recently and he missed out on the vacant Alpine seat to rookie Jack Doohan last week.
Ex-F1 driver Schumacher believes his nephew deserved the Williams seat though as he told the German Press Agency: "You can perhaps respect this decision because Colapinto is a driver from Williams' junior development program.
"But I think it is absurd and makes no sense from a performance perspective.
"I think the risk for the racing team and also the driver is much, much higher than if they had put someone with experience like Mick in," explained the 49-year-old.
He believed there was 'no amount in the world' that would justify the signing of the young Argentineand that Mick Schumacher was a driver who could 'take them further'.
"You have to be fair and admit that it simply took Mick too long in his second season at Haas to find his feet and get his teammate under control."
Although the former Williams driver added that 'Formula 1 is unforgiving'.
All eyes will be on Colapinto at Monza as he gets behind the wheel for his F1 debut at the Italian Grand Prix.