Sotah 12a - Gezerios of Pharoh to Throw in River

The Pesukim imply that there were 2 stages of decrees. The first was to the מילדות that they should kill the Jewish boys immediately as they are being born (abortion as i explained yesterday). The second was כל הבן הילוד היאורה תשליכוהו - that the boys are to be thrown into the river. However, the gemara says there were actually 3 stages of gezeiros:

1. The midwives should abort the boys.

2. The boys should be thrown into the river [rashi 12a seems to explain that the difference between #1 and #2 is that for the first there weren't any guards set up to enforce and for the second there were guards to enforce, but i am not sure why he doesn't simply explain that the first was to abort and the second was to throw in the river?].

3. He extended the gezeira to include even egyptian boys.

There seems to be a contradiction between the gemara 11a and 12b as to why Pharoh chose water as the method to anihilate the boys. On 11a the gemara says the reason is that they assumed Hashem would punish them מדה כנגד מדה (as we see in the end that they were in fact punished by water) and by using water they would be safe since Hashem promised not to bring a mabul (this was also their justification to enter the sea even though they clearly recognized that it split as a miracle for the jews). Yet on 12b the gemara says that there was a prediction from the future tellers that the savior of yisroel will be hurt by water, so Pharoh decreed that the children should be thrown into water as an attempt to kill their savior. Which one is it?

Moshe was born on Adar 7 (according to the second answer of the gemara it was adar rishon). Rashi (12a d.h. ul'basof) explains that on that day Pharoh's future tellers notified him of the birth and Pharoh responded by making the 3rd gezeira to throw even the egyptian children in the sea (which lasted for 3 months until 6th of sivan when he placed in the sea in a basket, and on that day Pharoh was comforted that he was killed so the gezeira was nullified).

Tosafos asks, how does the gemara say that moshe took credit for the fact that all those born after him were alive since he was the cause for the gezeira to stop; he was also the cause for the gezeira to exist in the first place!? Tosafos answers that gezeira #1 for the midwives to kill the boys was not attributed to moshe, rather attributed to the concern of the Jews overpowering the egyptians. Therefore, moshe was the first baby placed in the river (since the gezeira began at the time of his birth) and he can therefore take credit for the ending of the gezeira. The Maharsha asks on Tosafos that Moshe was certainly not the first baby thrown into the sea. If Tosafos is correct then no jews would have been thrown in the sea, yet many midrashim imply that they were (also, since gezeira #3 began on moshe's birth and lasted 3 months until moshe was placed in the sea, there were certainly many babies thrown in over the 3 months. But perhaps there were no babies thrown in for those 3 months, because everyone divorced their wives when amram did, moshe was born 6 months after amram took her back because she was 3 months pregnant, so no jewish babies would have been born until the day moshe was put in the sea which is 9 months from when they would have followed amram's lead and remarried their wives). Furthermore, although the 3rd gezeira to throw even the egyptian babies into the sea occurred when moshe was born, the 2nd gezeira to throw the Jewish boys into the sea preceded Moshe's birth.

The Maharsha explains that the 1st and 2nd gezeira both preceded Moshe's birth and were implemented out of concern that of הבה נתכחמה לו...פן ירבה...ועלה מן הארץ, only the 3rd gezeira was implemented because of Moshe. Once Moshe was thrown into the river and Pharoh thought that the leader was killed, he was mevatel all the gezeiros.

Now, the rationale for the choice of using water for gezeira #2 which preceeded the knowledge of Moshe being born, could not be because of Moshe. That is why the gemara on 11a attributes it to the fact that they determined that it was a good method to avoid being punished since Hashem would not bring another mabul. But, when it came to the "prophecy" that the savior was born and that he will be hurt by water, Pharoh extended the gezeira to the egyptian boys as well and insisted on water as the gemara 12 b explains since they knew Moshe would be hurt by water (which was true and fulfilled by mei meriva).

However, Rashi in chumash definitely doesn't prescribe to this approach because Rashi explains that even gezeira #1 when the midwives were told to kill the boys was because Pharoh already knew that Moshe would be born to save them.