Another option is to complain to the old maintainer. The new maintainer may be more likely to listen to the old maintainer than a random user.
Also if the changes are egregious, then discussing specifics in public, ideally on a module-specific mailing list, but you could do ithere or on use.perl.org, may make more people aware of the issues around this new maintainer. That may help convince someone else to undertake the fork of the module that you don't want to handle, and it may make others aware that this isn't a good person to hand over modules to.
Of course that option comes with the significant cost that you'll be reasonably likely to create some bad blood. I've always had the attitude that I'm willing to risk create bad blood if I think the cause is important enough. (That said I set the bar fairly high, and work to avoid accidentally creating bad blood.) However lots of people disagree with me on that.