We used to have a tradition in this country that "politics stop at the water's edge", meaning that both parties recognized the importance of the country speaking with one voice in matters of foreign policy. This was a sound policy, but democrats torpedoed it over vietnam and Reagan's fight against communist takeovers in latin america. Of course, it is easier to speak with one voice when there is broad agreement, and in our form of government, we can't just demand that people shut up if they disagree with the president. (I note that Woodrow Wilson and FDR among others, had just such a policy and put thousands of people in prison for sedition merely because they spoke out against WW I or II.) I think there is little to be gained from potential candidates grandstanding on this issue of egypt. We do need to speak with one voice. Obama is president, for better or worse, but he will have to answer for his undermining of the current Egyptian government. If there is a peaceful transition to a more representative government and the peace with Israel holds, he can rightly claim success. If there is a bloodbath, if radical islamists get into government or if the peace treaty is broken, he can legitimately be criticized.
I agree with those who think that the arabs are too smart to disrupt traffic on the canal or to not spend money maintaining it. The canal is a huge moneymaker for the operator. But let us suppose that they both disrupt traffic and fail to maintain the canal infrastructure. What should happen? What would happen? They would probably just get UN sanctions against them. I can't see anyone invading Egypt for real. The Navy might be able to force the canal open but it would still disrupt traffic big time and the world economy would feel the result right away. I think Europe would be in big trouble, the US less so.
Then had WW and FDR not incarserated those people who knows what their affect on the critical mass of popular opinion might have been led to. Which makes critiquing the acts wisdom unfounded. With Nam it turned out that had we never invaded and since it went red anyway we never should have gone in. The Cold War, had it been left alone, might just have evolved to what the relationship between China and the US is now. Modern governments are all some hybrid of commercialism with social management policies woven through them, in spite of all the banner raising. Some fanciful speculation on my part and I hope its understood as that.
I don't think we can wait around to use the canal while UN sanctions take effect. Hopefully, as you put it, their own interests should override their religiously inspired hate. Egypt must be one of the most trade dependant nations on Earth.