I feel like this used to work, but recently the helper has been giving me review comments about code that is being removed by the patch. It's hard to find an example since the suggestions are gone now in the patches that I have now reviewed, but a simple example is something like "function foo() should no longer be called because [complex explanation about why the patch has changed things]", where the call to foo() is being removed in the patch.
I tried looking for an example. I will update this issue when it next happens.