[jfman]

I just think they saw it as futile. I think the air of confidence is simply to avoid saying they will break the law.

For the, very likely, people Vs Parliament election it's better to have Ministers out using air time to say "we will deliver Brexit" than Peers dragging out proceedings all weekend.

Although I agree with a lot of your post - it's likely to end up in the supreme court on the point of can Parliament compel the executive in this way, regardless of how well or badly the Bill is drafted.