I think it is important to keep a few things in mind regarding the three intentions of the Militia.
Firstly, to pray for the pope falls under the fourth commandment, wherein we have a duty to pray for our parents and those holding authority. This certainly does not violate the principles of St. Louis de Montfort, since the commandments are part of our duty. The merits are given to Our Lady, but to pray for the pope is a meritorious act. We must be careful not to fall into a type of Quietism whereby our will is never fixed to pray for a concrete person, and thus one does not exercise a concrete act of fraternal charity. Simply to say that one prays for whatever Our Lady wants without ever specifying a prayer for what falls under ones duty in charity or justice seems to me to be problematic. General intentions need to be complemented with specific ones.
Secondly, the intention for the triumph of the Roman Church is required of all who seek a plenary indulgence, since it is one of the four intentions of the pope necessary for the gaining of the indulgence.
Thirdly, the consecration of Russia is expressly willed by Our Lady, and thus it is meant to be prayed for.
Joining this little group is certainly not required, but I think that praying for these three things is not exactly optional.