Not that it won't revive the machine and make it useful, but that it comes with a support cost.
Basically, being a fully paid up geek, and someone who has played with multiple operating systems for years, I can cope with using just about anything.
That's fine for me, but it's unrealistic to expect a teacher, with no experience of linux, to cope with student using open source products to do their work, or be able to fully support the student.
Basically it would be sink or swim.
To work, online learning needs a predictable environment that gives a degree of standardization. There's no reason why you couldn't standardize on linux, but you need to plan it properly. (Huayra linux from Argentina is an example of what can be achieved with an education focused distribution)
Windows and OS X both offer predictable environments and ones where one can assume the presence of certain browsers - edge and safari respectively and the presence of some standard applications. The joy of linux means you can't do that - while there are a lot of components in common, various distributions are different enough to complicate things, and as I showed some time back, if you are using an older revived machine, you may be using a less than mainstream distribution.
So my heart sank when I saw an article in the Register about taking an early 2007 vintage Macbook (one of the early intel based machines - the article doesn't make that entirely clear) and sticking Elementary OS on it.
Actually, I'm lying when I said my heart sank - I actually thought it would be a fun thing to do, well except that no one's selling polycarbonate Macs on ebay in Australia for fifty bucks - more like a $150, and that's too much for a fun project.
But reviving a machine is only the start of it - if you provide it to someone you need to provide some support, and if you have multiple linux's which do you support?
Consider the start menu. In Xubuntu it's at the top left. Gnome or KDE distributions usually have it at the bottom left, and OpenBox based distros like Bunsen Labs prefer you to right click on the desktop.
Nothing wrong with any of them, but a nightmare to support.
So while I'm all in favour of reviving old machines by running linux on them - basically there are social and environmental positives in doing so, I'm well aware of the support costs involved and why, to succeed, any project needs to have a carefully thought out end user support plan ...