The mishna said in the 3nd chapter of Eruvin mishna 1-2:
מְעָרְבִין לְנָזִיר בְּיַיִן וּלְיִשְׂרָאֵל בִּתְרוּמָה ... מְעָרְבִין בִּדְמַאי
We can make a Eruv for a nazir by wine, for Yisroel by teruma, with Demai. The dmay is not really allowed for a not poor neeman man. But it is good for Eruv.
We can assume that Egg Matsa is not considered as prohibited as Chomets, some people do not eat this by minhag. May be that it is similar to Demay from this point of view. The case of Nazir which can ""Lehishael" and truma too are perhaps an additional proof for the egg Matso minhag which can also be nish'al. I heard that the Steipeler זצוק"ל was stringent to eat "not Gebrocht". When his spouse deceased, he was invited to his daughter. When he saw that she made stringent efforts to make not gebrocht, when in her home they was eating Gebrocht, the Steipeler has decided to make Hatarat nedarim in way to eat gebrocht.
So Eruve Chatserot with eggs Matsot are apparently regulatory.
I am duty to @Double AA for indicating this post.