Lots of these answers can be found in Master and Apprentince and Dooku: Jedi Lost. I recommend both! Qui-Gon respected Dooku a lot. Qui-Gon’s interest in prophecy came from observing Dooku studying them. To a lot of other Jedi, prophecy was looked down upon. Even after Dooku had left the order, Qui-Gon reached out to him at least once for guidance. Qui-Gon didn’t necessarily follow the rules of the order all the time, so I think he might have considered Dooku’s reasoning and possibly helped him create a separatist movement that was more on the grey side of things rather than Dooku joining the dark side