Any recommended readings on the "unable to estimate" claim?
It's just that estimating well needs people with training on how to do that, and then it takes substantial time to make good estimates. And there will still be significant error bars (if the estimate isn't a range, it doesn't count as an estimate). But it's certainly doable.
To narrow down the estimate to what they want would take just as long as just doing the work.
It’s this sort of disinformation that perpetuates the contingent of software developers that cry bloody murder whenever they’re asked to say if something will take a day or a year.