Saved from drowning by Moshe

The gemara (Sotah 12b) describes the setting of Moshe's birth as follows.
1. Paro's advisors saw a star that represented the birth of Yisroel's savior.
2. They were not sure if he would be a Jew, so they advised to have all children (even Egyption) thrown into the sea.
3. The astrologers saw, through the stars, that Moshe had been placed in the water. They thought that to mean that the danger had passed.
4. Paro cancelled the decree to have all children thrown into the see.

The gemara then relays Moshe's comment that Klal Yisroel owed him appreciation: "It was only due to me - being put into the sea - that you were all saved. Had that not happened, the nation would have been drowned."

I don't get it. True, the decree was only cancelled because of Moshe. But it was only enacted because of Moshe as well!

In discussing this with my father shlita over Shabbos, he suggested that this is very similar to what happened with Mordechai. Mordechai instigated the fight with Haman that endangered the Jews, and is then given much credit for leading us to a advantageous resolution.

Is it possible that one must thank someone for helping him when he created the problem? Did Yosef owe his brothers appreciation for pulling him out of the pit after casting him into it? I find that hard to imagine!
When Chazal discuss the reasons for the decrees of Purim, Mordechai is not even mentioned. He was doing what he had to, and there could have been no way that would have lead to disaster, unless the tragedy was otherwise iminent and deserved. In fact, the conclusion of Purim - "Kiymu Mah SheKiblu Kvar - was that the people accepted that the actions of and enactments are made by the Rabonnim for the sake, and with the knowledge of, the Torah. They repented blaming Mordechai for causing a tragedy that he was incidental to.
We can suggest that a similar thing happened with Moshe. At some point the desperate Egyptions would have ordered the drowning of all Jewish children. Had that happened, the decree would have continued until there was no more nation, chas vsholom. Such a decree did not happen though, since the first time the thought of drowning children was floated, it was targeted Moshe, and included even the Egyption children [in theory]. Such an edict clearly could not be maintained indefinitely. As soon as the threat passed, the issue was cancelled, and was probably too sensitive a point to be raised again, even had Paro wanted to.

Perhaps a support can be found in the eventual retribution of the Egyptions. They are drowned at sea, as punishment for drowning the Yisroeli babies. Despite the fact that the decree was relatively short lived, and included Egyption babies as well [although the Egyptions might not have complied with their own children]. Perhaps though, since they intended to make such a decree against the Jewish children, and only had to abandon the idea because of the way it worked out with Moshe, they are credited with having carried out their original nefarious intentions.