One advantage of Solus over Manjaro is the absence of user repository.
While AUR might be very helpful it is just like installing random stuff received by strangers. Some repositories have been abandoned and thus may leave vulnerable software, some may contain malicious code, many contain illegal code because for example license does not allow redistribution, etc.
Also a rolling release, is certainly not the best choice for education because even if Manjaro is safer that its parent, it still suppose to make frequent updates and read the Arch blog before doing so since some manual interventions may be required on that distro. There are some distribution that specifically target education and that would certainly be a better choice for this specific use case as having a stable system with adapted software and settings are more important to allow teachers and students to focus on education rather than having the last version of the software and perhaps having to deal with some issues that may come along (either technical or some functional changes that may lead to differences between the training material).