Essentially he found no evidence that clearing habitat near leafy greens reduces E. coli contamination. In fact, his research provides some preliminary evidence that habitat removal could actually increase food safety risk. However, it is not clear that companies buying greens have gotten the message, and some of them are likely still requiring or encouraging farmers to destroy habitat.
When you buy greens, please reach out to the company producing / packaging the greens, and ask them to discourage farmers from clearing habitat (sample text you can use in an email is below). You can also talk to the staff at the customer service desk of the grocery to ask them about their sourcing criteria, and pass on the information about this research.
Thanks for helping to protect wildlife habitat!