https://www.tue.nl/en/news/news-overview/17-06-2019-tue-vaca...
Where did you read about "18 months"? Sounds like "first 6 months" to me. In my experience searching for good academic staff, especially in fields with a lucrative industry takes ages, so I wouldn't be too sure that there will be a strong discriminatory effect when there are not that many women to recruit anyway.
I agree that this move is not the best one. It will end up sending the wrong signals again, which will just lead to backlash on women working in STEM fields. Attacking with opposite discrimination is certainly a bad temporal fix for an existing systematic bias and the tendency of men to downplay competent women.
However, this tendency costs society a lot. It is a fix at least. Someone listened.
I wouldn't expect that they want to make this permanent once things have equaled out a bit.