Poor attitude on field... I'd say that's frustration more than anything due to the fact he's expected to do everything because of incompetent halves.
Does he even have a poor attitude on the field?
The best determiner of "attitude" in modern sport is metrics. The American sports analysts use statistical analysis to measure attitude since the trend in American sports is to look disinterested for the main part - then have the "explosion" of emotion on occasion.
For mine that's what a lot of young footballers are doing now. Look at Kalifa Fai Fai Loa --> he plays it cool all the time, but when he makes the outstanding play he erupts emotionally. Has he normally got a poor attitude?
Metrics clearly show that he is highly involved in games --> that's the result of a GOOD attitude on field.
Take Hindmarsh - how do you know if he's got a good attitude? Metrics. Nobody just keeps on tackling if they're disinterested.
But then you have the "exceptional effort" which cannot be measured, only observed: Hindmarsh chases everything.
If Stuart watched Hayne play, he wouldn't need metrics (which show good attitude for Hayne) - he'd see that Hayne too chases everything.
Headbutt was ridiculous - and if you can't coach, you would stay clear. Kearney can coach, so he saw no need to drop the guy for that. I'll bet any other coach would see that as a brain snap rather than a general poor attitude.