not if the end cap is properly designed and fitted/maintained. The end cap should provide some resistance to coming off the axle.........it also provides the end seal. On my Dt Swiss hubs it usually requires adjustable pliers with a piece of cloth wrapped between the jaws to remove the end cap. So you should be able to unscrew the cassette and remove it whilst the frehub/ratchet stays in place until you remove the end cap.
As I said I have DT Swiss hubs/ratchet freehub so dont know if the end cap fitting is the same on others...but on the DT Swiss the end of the end cap has a thin metal rim and that "clicks into place. Maybe with sticky rubber gloves it can be removed by hand but for removal it has to levered to one side and then pull and there is not much to grip onto.....when replacing it needs a tap to click that thin metal rim into place. There is a rubber ring seal on the inside of the cap....that should be greased. I have 2 bikes with the DT Swiss 350 hybrid hubs and owned another with the same set up previously.....all the same.
