Just remember, Alexi has his father's madness, and even if it's just barely starting to manifest, it could very well lead to the paranoia and retraction from anything that doesn't fit in or go along with what Alexi's imagines as right. So no, he trusts his brother, in fact, because of what he has been told, he technically trusts Mois more than Joseph, kinda, but he trusts Joseph to know more, while he trusts Mois to know the most important thing :P

If he knew about Erik he would; freak-demand to see Alexi-calm down-rescind order-spend the whole night worrying :P