Perhaps the comment was edited, but there is no wording in the current post that states battlegroups are in Iceland just that Iceland contributes to battlegroups in other countries.
Well... tis true that there is a mine clearing group to deal with the occasional mine that drifts in from the old WW2 mine fields in the North Atlantic. And they did send one of them over to participate in the Gulf War...
https://www.icelandreview.com/news/iceland-featured-the-dail...
...but there are still no battalions in Iceland. There isn't even a permanent US air base any more, they cleared out in the 2000´s.