Although I do agree with you, that study claimed a continental North Sea ancestry was as high as 76% in the skeletons they analysed.

The 50-100% example is an example of an older and relatively lower quality study that can’t be used as well to analyse the DNA of groups from so long ago, as the paragraph just below it says:
>”However, populations change over time through drift and gene flow, so present-day populations may be poor proxies for ancient groups of unknown genetic makeup”.