This doesn't exactly make her a "cheater" though, does it? The general election electorate and a primary electorate are two different things. If you don't believe me, talk to Ned Lamont.
If you are referring to her accepting the cross-over democrat vote, no, that's not cheating. The article reads like the author takes exception to her willingness to deprive a candidacy resulting from a republican primary process because she didn't like the results. I think she is called a cheater because she “cheated” the majority of republicans (as in primary voting republicans)out of their chosen candidate. In effect, we had the republican primary all over again, this time with democrats allowed to vote in it. Thus the cheater referance.