If you are worried about duplicates, aka a single bot spamming multiple votes, then that's feasible to mitigate.
If you are worried about multiple bots spamming one vote each, that's harder to mitigate and it comes down to how the instances handles bot accounts in general. IMO it's best to ignore the bot problem and instead focus on designing a vote weighting system that favors similar instances.
While the consumption for AI train can be large, there are arguments to be made for its net effect in the long run.
The article's last section gives a few examples that are interesting to me from an environmental perspective. Using smaller problem-specific models can have a large effect in reducing AI emissions, since their relation to model size is not linear. AI assistance can indeed increase worker productivity, which does not necessarily decrease emissions but we have to keep in mind that our bodies are pretty inefficient meat bags. Last but not least, AI literacy can lead to better legislation and regulation.