That doesn't matter.Just another point about demon and devils and why it doesn't really apply here.
The meaning of demon or devil in D&D isn't (much) different than the commonly understood meaning. Big, bad, nasty evil thing that eats souls is pretty much the definition of demon or devil. Additionally, demons and devils in D&D are the antagonists. They are the stuff you fight against - again, very much in keeping with the intent of demons and devils in real world beliefs.
In other words, instead of substituting a new meaning, imposed by the authors of D&D, as is the case in phylactery, demons and devils are not culturally appropriating anything. The meaning is largely unchanged and the intent of the concepts is kept.
Unless you believe that a phylactery is created through a thoroughly evil act (3e definition), or that it needs to regularly fed souls (Paizo definition) the definition of phylactery is definitely being changed quite a lot.
Some believers were obviously upset about the use of Christian terms in D&D and when the point is to be respectful towards religious groups it doesn't matter if you think that the terms where used correctly or not.