I think the question of good data handling in consultations is a wider one - it particularly annoys me when they're treated as representative surveys. However, in principle, you don't have to always use all the data you collect for it still to be useful. If you consult on a random road change and see that the data is roughly representative, fine. If you consult on cutting childcare and discover all the respondents are 70-year-old men, it's maybe time to widen the net.
Even if the council never uses the data immediately, it could still be useful for interested groups trying to challenge or interpret the findings later. Equally, the council may use it to understand why a specific intervention which seemed to be supported has actually failed or faced later opposition.
I was talking to someone who works for an English council recently and they said that they noticed their transport priorities consultation just wasn't being engaged with by a part of the city largely populated by Indian immigrants. They put someone on the ground and discovered that people who had a car wanted less congestion, but most people didn't have cars and were sick of the buses were rubbish. They also hated crossing the nearby main road to get anywhere. None of that came through in the original consultation. Working at diverse representation is important, and the first part of that is understanding where your data is coming from.