St Philoxenos is one of my favourite saints because he was so powerfully straightforward. Read his depiction of a glutton - not even the most incorrigible couch-potato could remain unmoved!
I think that the possible misunderstanding of what he is saying comes from the fact that, being a translation the word "passions" has to be used, but cannot, without a lengthy footnote, explain why he denotes all passions as being negative. It is quite simply because the passions he writes about are derived from our sinful, selfish nature, which can be summed up as
"I want , give me!" It took a lot of spiritual labour to identify, if not positive passions, then at least a positive aspect to some of the passions, for example anger, which can obviously be misdirected, and usually is, but which can be used as a weapon to fight against sin.
We are born into the natural world and "natural movements" are our responding to the non-spiritual, animal aspect of who we are. Lust for sex and food are "natural" to our fallen state,but drag down our spiritual, or real, selves.
Anyway, Roberta Chestnut's book "Three Monophysite Christologies" shows its uselessness by its very title because the three saints she deals with were not monophysites but Orthodox Christians.
I shall return to this another time.