Arch Linux Wiki has said explicitly that they don't have any responsibilities about what a package in AUR does and they also say that it's mandatory to read and understand PKGBUILD (or any other file or patch that a installation requires) before installing any package. But when a package gets updated and those who have enabled notifications want to update the package, they should (I would say everyone must) click on package page, view changes, and click on latest commit to see what has changed. So appending latest commit link "helps" and "encourages" people to check latest update and I don't think in any possible way has a downside except for a little more text to email which I assume it's OK.