We have a GitHub (Enterprise) organisation whose canonical name is "FooBar".
However, we have a Multibranch Pipeline that uses a GitHub Branch Source with owner "foobar". In this case, the branch source GitHub ignores incoming webhooks, as String.equals() is used (e.g. in PullRequestGHEventSubscriber).
GitHub is very lenient when checking out repos, e.g. git clone firstname.lastname@example.org:fooBAR/AnDroiD.git works fine for the FooBar/android repo — so it seems likely that people will end up configuring jobs using a non-canonical capitalisation of the user/org name.
The repo name comparison should likely be case-insensitive too. The repo name is usually configured via a dropdown, so it should have the canonical case, but I also configure MB Pipelines with the Job DSL plugin, so the possibility for error remains.