Is Paul a Flip-Flopper?

FFoB 17: Paul's Change of Plans
(NIV) 2 Corinthians 1:15Because I was confident of this, I planned to visit you first so that you might benefit twice. 16I planned to visit you on my way to Macedonia and to come back to you from Macedonia, and then to have you send me on my way to Judea. 17When I planned this, did I do it lightly? Or do I make my plans in a worldly manner so that in the same breath I say, "Yes, yes" and "No, no"?

18But as surely as God is faithful, our message to you is not "Yes" and "No." 19For the Son of God, Jesus Christ, who was preached among you by me and Silas[b] and Timothy, was not "Yes" and "No," but in him it has always been "Yes." 20For no matter how many promises God has made, they are "Yes" in Christ. And so through him the "Amen" is spoken by us to the glory of God. 21Now it is God who makes both us and you stand firm in Christ. He anointed us, 22set his seal of ownership on us, and put his Spirit in our hearts as a deposit, guaranteeing what is to come.

23I call God as my witness that it was in order to spare you that I did not return to Corinth. 24Not that we lord it over your faith, but we work with you for your joy, because it is by faith you stand firm.

Apparently, what happened was that Paul's "No" became a "Yes" when he visited Corinth directly instead of via Macedonia. The Corinthians were totally unprepared for his visit. Then Paul's "Yes" became a "No" when he said he would return, but instead he wrote a painful letter in place of himself. His enemies now accuse him of being a flip-flopper.

This is a damaging accusation because keeping to one's promise is an important sign of integrity. The lack of it is detrimental to the trust of his followers to his leadership. (This is how John Kerry lost the election to Bush in 2004) What is Paul's defense?

Yes, there has been a change of plans. But a change of plans is not the same as a change of message. So even though Paul did not keep to his promise of coming late or returning early, the cause of his decisions is the same. He did it because he love them. So regardless of his difference in plans and actual execution, he is always saying "Yes" to them.