I don't know too much about Coptic Church politics, but I would like to point out that His Holiness Pope Shenouda served as a bishop prior to being elected pope. I know it's against the canons that OO still take very seriously (we really don't do this in the EOC anymore) and people did protest His Holiness' election, but it went through and he governed the Coptic Church for 40 years.
HH was a bishop for social services, or a general bishop. There's some disagreement as to what a "general bishop" is since it has no precedent in the past. While the jobs of a general bishop is similar to a chorepiscopos, a general bishop still has full membership of the Synod. HH Pope Kyrillos VI (+HHPKVI), predecessor to HH Pope Shenouda III (+HHPSIII), started the role of a general bishop for social services. At some point, some people see social services as equivalent to a diocese. +HHPSIII (as Bishop Shenouda) was quite irate at +HHPKVI for designating another bishop as bishop of higher education as interfering with his "diocese of education". In addition, it seems that +HHPSIII as a layman wrote against HH Pope Yousab mentioning how when the church broke this particular canon, there was a subsequent "26 years of darkness and corruption."
In any case, +HHPSIII seems to have changed his mind, perhaps seeing that his bishopric was not a diocesan bishopric anymore. In addition, under his administration, he multiplied the office of general bishops partially for the purpose of gaining power in the Synod, which in his early days in the throne were not favorable for him.
Now +HHPSIII lead the church well, but his mistake seems to be not solving this canonicity issue in due time that he also had a problem with before being a monk. His other mistake is the high number of "aimless" general bishops in the synod who seem to be useless. On top of this, we are having a patristic revival in the Coptic church, and more of her members are educated than ever before. There is a precedent indeed that the few times bishops became popes (only on the 20th century) have been dark times for the Coptic church.
Personally, because of the implication of being married to a diocese, I agree that there should be no bishop who should be pope. That doesn't take away the fact that +HHPSIII has done more good for the church, despite any drawbacks he may have had. St Gregory Nazienzen was a great theologian and saint of the church, but his actions to move from one diocese to another was not without harsh criticism, and lead him to resign from his office, which was another cause of admiration for him, so that he avoided more trouble for the church. I think it's pretty clear there is a growing number in the Coptic church that are not joking around about sticking with this particular canon, and for the sake of the peace of the church, I hope these candidates who are are bishops take a page from St Gregory and step down.
And I hope whoever the new pope would be to get rid of the office of general bishop or clarify then as chorepiscopos. I also am against bishops of social services. I believe these are the functions of deacons and archdeacons.