Oh right...I forgot about this, but we have something in our cucumber environment that enforces the use of the `expect` syntax in our cukes because we want it to be shown in docs as we consider it the primary syntax moving forward:

https://github.com/rspec/rspec-core/blob/master/features/support/require_expect_syntax_in_aruba_specs.rb

The solution is to tweak that file like we have it in rspec-expecations:

https://github.com/rspec/rspec-expectations/blob/9febc53557ccec50bd2549b3bedc77e94b603a2b/features/support/disallow_certain_apis.rb#L6-L8

...so that it allows scenarios tagged with a particular tag to use `should`, `stub`, etc.