Nothing to contradict... 100BC is still not 270BC... do we have any evidence of Germans/Celts at 270BC? No... the description of Gallic or Germanic peoples at a time much earlier than recorded simply cannot be attributed or associated with the particular circumstances of a later time, especially when we have no evidence.

As mentioned, for the Late Period Project, if any Celtic faction people want to argue for them being weak in general, or strong, but much more strong than Germanics, I'll point them to these threads where you have ample evidence that the internal politics were hardly the single reason they succumbed to Germanic aggression.