I'd like to make another observation about Piper's pacifism:
Take these two related statements:
4. Jesus set the stage for a life of sojourning in this world where we bear witness that this world is not our home, and not our kingdom, by renouncing the establishment or the advancement of our Christian cause with the sword.
5. Jesus strikes the note that the dominant (not the only) way Christians will show the supreme value of our treasure in heaven is by being so freed from the love of this world and so satisfied with the hope of glory that we are able to love our enemies and not return evil for evil, even as we expect to be wronged in this world...  Our primary aim in life is to show that Christ is more precious than life.
i) There's the implicit assumption that love is divisible. It's as if he thinks love is quantitative, so that if you love my wife, then you love Jesus less. The more people you love, or the more you love one person in particular, the less you can love each person individually. There's only so much love to go around. A finite commodity. If you have two kids, you love each kid half as much as if you only had one kid. If you love my wife, mother, son, kid brother, and best friend, then you must divvy up your love five ways, and there's not much love left over for Jesus.
Loving Jesus is in competition with loving your mother, or your kid brother, or your best friend. The more you love them, the less you love Jesus.
Likewise, you can't love Jesus as much if you love hiking. Loving one thing subtracts from loving another thing.
This is very muddled thinking. For one thing, it fails to appreciate than love is qualitative rather than quantitative.
In addition, it fails to appreciate the fact that there are different kinds of love. Romantic love is different than parental love. So even if love was divisible or quantitative (which is not the case), one kind of love can't subtract from a different kind of love.
ii) Related to this is Piper's failure to appreciate that we can love God by giving and receiving love from people other than God. God can express his love to us through natural goods.
As a rule, we don't experience God directly. Rather, we experience God through a natural medium. It creates a false dichotomy between the gift and the giver, as though, if you love the gift, you can't love the giver. But natural blessings are a source of gratitude and praise. God isn't normally available to us apart from the world he put us in.
iii) To some extent, Piper's view seems to be a throwback to the ascetic view, where loving God requires self-denial. All the things you must give up to love God. Pure, disinterested devotion.
A problem with that is that, as creatures, we have natural physical and emotional needs. God made us that way. That's not worldly. That's a part of God's design for humanity. That's no more worldly than my need to breathe oxygen.
iv) In fairness to Piper, there are situations in which allegiance to God can be in competition with other things. Take people who grow up in church, then go to college, where indulge in premarital sex.
Mind you, that's an artificial choice. Normally, you don't have to choose between sex and Jesus. You can have both. The problem is sex outside of marriage.
Likewise, there are persecution situations when you are forced to choose between Jesus and friends or family. But once again, that's an unnatural choice. That's imposed on you.
iv) Piper's view generates a false dichotomy. And if people took it seriously, it would drive them to apostasy. In general, these are complementary goods rather than competing goods. For instance, a happy family life is a source of thanksgiving. That makes Christians more grateful, more worshipful, not less so.