I think they mean the research data won't be used directly to target ads or try to make sales to you (standard guideline for market research), rather than the second order effect of allowing them to improve their overall ad targeting which then affects you.
not necessarily - the data could be used to understand overall usage patterns and preferences in the target population as a whole - much in the same way as traditional surveys and focus groups. If indeed it is put into ML which then tries to match the data with the actual participants, then I agree that that is misrepresentation and probably criminal.
1. Google's entire business model is advertising through collecting more complete user data.
2. Why would they collect this data if not to further their advertisement business?
3. I've never heard of companies collecting data that wouldn't further their business pursuits.
This data is either "digital-oil" or "digital uranium" both still extremely valuable.