I am arguing nothing here Kai, simply presenting information for consideration. That is why i said that these images "seem to help establish" rather than "here is the evidence that this is true."
I do believe, however, that one can find a great deal of commonality between these old bird-like gold hilts and various depictions of the Sarimanok. They do indeed seem to be abstract bird heads and they look quite similar to many established depictions of Sarimanok.
Here is some further information about the Sarimanok gathered from the internet. There are numerous origin stories so it is difficult sorting out what the actual development of this mythological beast actually is, but it is clearly an old and important symbolic creature to the region while one can find little to nothing showing the importance of kakatau (cockatoo) to the Moro.
BTW, it does seem that most sources of information that i encounter seem to define the word "Sarimanok" as Sari-article of clothing, usually colorful and Manok-chicken or bird. So the Sairmanok is seen as a colorfully dressed bird. In some stories it seems to have its roots with the Maranao totem bird called Itotoro who has an invisible spirit twin called Inikadowa and together they act as a medium to the spirit world.
Another theory is the the Sarimanok came from the Garuda and then developed into its own creature. It does appear, however, that it did exist in Maranao lore before the arrival of the Spanish.
The FMA blog linked here cites its use as a symbol of resistance against the Spanish. Perhaps another reason why such a symbolic presence might end up being represented on a kris used to fight in such resistance.
And yes, none of this is particularly back up by any strong extant sources that Kai (and i believe all of us) would like to see. But i must remind you Cato's hypothesis that the pommel of the kris that we speak about here might represent a kakatau does not really have any more evidence behind it either.
http://pinoy-culture.com/the-sariman...of-lake-lanao/
http://12fma.blogspot.com/2008/06/sa...no-spirit.html
https://en.wikipedia.org/wiki/Sarimanok