The article seems to engage in a bifurcation fallacy in suggesting that if you have company data on a personal device, then you must or ought to have MDM.

Trusting me to be able to access my work e-mail from my own equipment without the need to monitor me is perhaps the lowest baseline of trust that I expect an employer to put in me. Afterall, if they can't trust me to be responsible with such data why bother giving me access to their systems at all?*

* The exception of course is in cases where they are required to monitor data use by law, e.g. medical. But prefer working in open environments anyways...