There is no need to add a check for the page_cache_invoke_hooks variable to be enabled to allow for redirect to enable caching. It looks like the only reason you'd need page_cache_invoke_hooks enabled would be to support deleting unused redirects. I'd suggest just changing the description to inform that caching will prevent redirect cleanup when page_cache_invoke_hooks is not TRUE.
Creating patch file now.
Closed: outdated
1.0
User interface
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
Take a look at the referenced issue #2760089: Is $conf['page_cache_invoke_hooks']=TRUE really required for Redirect cache? → , marking this as outdated.