It's pretty clear that Morsi is acting for the short term. Pushing through a form of constitution that favours one political party over any others is hardly in the national interest. It's also short-sighted. Given this display of power from Morsi, what is to stop a future government of a different political colour from taking advantage of its power to further amend the constitution? A constitution is a statement of parameters, and should not contain words that limit the way people behave. Rather, a constitution should take a form that envisages the maximum amount of freedom to speak, to work, to organise, or to live. It is not a place where you specify how media outlets should be formed - that's to be done through a law specifically for the media, for example.
Morsi is being pushed to alienate parts of Egyptian society by his party platform, and these biases are entering into the creation of a document that must assist - not hinder - the enjoyment of independence of the largest number of Egyptians possible. Morsi's supporters might say that winning the presidential election gave the Islamists the right to take the steps they are taking, but this is untrue. Morsi will always rule under a cloud if he continues to take the avenue he is going down, and for many Egyptians the founding document of the country's polity will always remain tainted by association with one particular political party.
What Morsi should do is to assemble a representative assembly that can objectively draft a constitution that would accommodate the worldviews of the maximum possible number of Egyptians. Instead, it seems that the important task of forming a constitution for Egypt is becoming a political football. This kind of thinking will surely fail in the long term, and Morsi would be advised to step back and think a bit more soberly about the real significance of a constitution in the history of any country. In the current climate, and if ratified, Egypt's new constitution is certain to last only as long as his term in office lasts. Given current popular sentiment, that might be quite a short period of time indeed.