Idol releases are much more time sensitive than standard artists. The built in base is huge but fickle, and I simply do not agree with any spin suggesting it was in her best interests to have her single and album delayed until Late March/Late May.
In addition, the choice summer tour opportunities are worked out in the spring. She would have had bigger sales numbers to negotiate with bigger acts if she released her album in March. Plus, she'd have been available to tour in May, which is when the big tours begin.
Her being pushed back actually jeopardized, not helped, her chances of scoring a big summer tour... of which she now has none. Management screwed her, period. At least that's my most humble of opinions.