I am very grateful for all the posts I read.
What is the rubric and why is he not following it? A lot depends on answering these two questions.
The reason I did not mention the rubric is very simple: it seems a lesser thing. Something that can be done away with without much issue (it seems). And yet it is mandated. I also hoped to reach some generic understanding, rather than seeking an answer to a specific issue.
The rubric I am referring to is the one found in the Roman Ritual concerning Eucharistic Adoration. §85 and §93 state that when the Blessed Sacrament is exposed in a monstrance, incense is to be used. There are two rubrics, one after the other, stating this. One says “incense is used”, the next says “the minister incenses the sacrament”. This is quite clear: it is not optional.
Now it is no surprise that someone would not use incense. In the Holy Mass, use of incense is
optional according to GIRM §276 (“
Incense may be used optionally”). If someone studied diligently the GIRM, he would know that incense is optional. It is possible someone would assume it is also optional in Adoration. So I do not blame anyone for not using incense in good faith. Also, I understand sometimes smoke alarms can be a concern. I myself served as acolyte in a Missa Cantata in a small chapel once, and the Mass had not even started when the smoke detector went off and firefighters showed up.
The point is that if someone is not accustomed to using incense, would not want to use incense simply because, or cannot use incense due to smoke detectors, the Roman Ritual specifies an additional, perfectly valid form of Eucharistic Adoration, where incensation of the Blessed Sacrament is optional: namely, exposition within a ciborium.
I hope you keep being patient with me. Why do we incense the Blessed Sacrament in the monstrance? Because it is such an incomprehensible honor that Christ would be there for us, exposed in a monstrance for us to adore Him. The saints themselves called this sort of adoration the greatest act of worship besides the Holy Mass. Saint Alphonsus Liguori said that “amongst all devotions, after that of receiving the sacraments, that of adoring Jesus in the Blessed Sacrament holds first place, is most pleasing to God, and most useful to ourselves”. Saint Pius X stated that this practice is " the fountainhead of all devotional works". St. Peter Eymard stated:
Eucharistic Adoration is the greatest act of holiness on earth. …] The adoration of Jesus in the Most Blessed Sacrament is the end of the Church Militant, just as adoration of God in His glory is the end of the Church Triumphant. A holy rivalry, a concert of prayer, a harmony of divine service should exist between the heavenly court and the Eucharistic court here below
This is how much I love Eucharistic Adoration. Therefore, when I see that something “minor” (even ridiculously minor, in the eyes of some!) is being omitted which is supposed to be done to honor and thank our Lord for a privilege we could never deserve in a lifetime, to stand before the exposed Eucharist, I wonder whether I should be doing something about it, at the risk of hurting or offending a very holy and pious priest and trespassing my role as a simple lay faithful, or whether I should simply let it go and offer in my heart that which may be lacking in the exterior act of adoration.
For some of us, things like this constitute a significant part of their spiritual warfare, so please be patient if you don’t quite see why things like these can take someone’s peace away. I simply seek no trouble and want to understand just how strict a lay faithful is supposed to get in these circumstances

I also don’t know what is worse for my soul: to remain silent about a liturgical omission, or to correct a priest of Christ. Love you guys
