Here is how Target could easily evade the WARN notice requirement:
1) There is an exception to the 60 day notice requirement for "unforeseen circumstances" (i.e. a recent massive data breach). That could easily buy them down from the 60 day requirement (companies facing this are supposed to notify "as soon as they know" a layoff could happen - which could be as little as a few days in an extraordinary situation).
2) The penalty for failing to notify employees is up to 60 days back pay to employees (severance packages are likely to include at least that). The employer has 3 weeks to satisfy the back pay requirement or an additional penalty of up to $30,000 ($500 per day of not notifying - up to 60 days) can be levied (I think they can handle that).