Normally I'm a big fan of passing functions around like this, but in this case you're interacting with a superclass which [has its own behavior](https://github.com/twisted/twisted/blob/trunk/twisted/application/service.py#L196).  There are definitely things which will inspect the `running` state on an `IService` provider (arguably it's a bug that `MultiService` doesn't do that), so this should probably be unconditionally upcalling to `super.startService` and `super.stopService` before invoking the `start` and `stop` callables.