how long is for ever?

One thing that report does not take into account is the no. of pages. An index with only 2 pages is not worth rebuilding or even reorganising. Accepted value for no. of pages in an index before its worth de-fragmenting is 500 - 1000. Therefore you can ignore the recommendation to rebuild this index.

Having said that a rebuild on that index should be almost instantaneous. I have heard of issues such as this being resolved by running dbcc updateusage.

It is worth checking for blocking as well.