One of the defences I am seeing is that he's a different generation and it's hard for him to adjust.
No no no no.
His 'generation' is in charge of labs across the world, deciding funding, encouraging and discouraging researchers, making and destroying careers careers.
His generation are responsible for the leaks in the 'leaky pipeline' (where women leave STEM at faster rates than men) and the fact that rates of women in STEM at high levels have stalled in many fields.
His generation is responsible for a system where a woman's name reduces the value of identical work (http://gender.stanford.edu/news/2014/
His generation is responsible for a system where women are blamed for wrecking their careers when they choose to have children. (http://mediarelations.cornell.edu/
Before anyone squeaks that I am being unfair, I know that Tim Hunt and men like him did not create the problem of socially embedded sexism. However, they are in charge and therefore responsible for working to fix it, not entrench it.
His generation have achieved great things in their fields and mistaken that for confidence that their every word is golden. (Clearest example - Richard Dawkins). They have reached the positions of power at work where people stop criticising them to their face and start nodding in agreement with every inane thing they say. That's why it was such a shock for him to hear the reaction from outside his bubble of 'people like him' and 'people paid to agree with him'.
His generation grew up with feminism all around them. They watched the world transform as the formal barriers against women in these fields were removed and saw firsthand the difference it makes. His wife is a Professor of Immunology.
He has no excuse whatsoever for his damaging ignorance and unexamined sexism.
In addition, women facing sexism have been told to wait for this generation to die off for almost as long as Tim Hunt has been working. It has not happened yet and it is not going to happen by waiting passively for it.
I read a review (and now I can't find it, to my deep frustration) which highlighted the barriers to women in STEM fields and noted that the sexism they were forced to fight against came from colleagues and junior staff AS WELL as from senior management. The pressures also come from other women because when you are powerless to change a system which is fundamentally sexist, then one or two women can make their careers by joining in and becoming sexism's enforcers.
These problems are structural, entrenched and endemic. These are big, hard problems to fight. It is not FAIR to expect the group who are already struggling under an unfair burden to also take responsibility for changing that system. It is also not POSSIBLE because the system protects itself, sheltering and promoting male sexism and punishing those who speak out. We need men to actively work at this too.
The other reason we cannot just wait for this generation to die off is that we are still actively training their replacements. Another story I have seen this week is about girls at a Florida school who were sent home from their final exam for wearing skirts. Another generation of boys and girls has just been taught what I will call Tim's Law
"There is no cost to women's careers or education that is too high to demand in order to protect men from their own sexual feelings."