Chapels in homes and priests celebrating Mass in those chapels as well as reserving the Blessed Sacrament in those chapels was once common, especially in the upper classes in Europe. The Church never forbid the practice, but such became rare for a variety of reasons: costs involved discouraged the faithful from establishing and maintaining such chapels, the faith waned in much of the upper classes, Protestant persecutions, however slight, of Catholics tended to encourage Catholics to band together more (and the upper classes in America tended not to be Catholic anyway), and an insufficient number of priests being available in the New World to provide for the needs of parishes prevented priests doing such things.
Frankly, I think it is you who are being unreasonable here. Have you not paid attention to what is going on in the SSPX during the past few years? Rather than trying to get this man to abandon his safe haven against the coming destruction of the SSPX priesthood (which will happen when the SSPX is regularized and there is more cooperation between the SSPX and the Conciliar bishops), perhaps you should seek to cling to the lifeboat he has created in his home.
By the way, in answer to your question about Canon Law, I found the following:
In his commentary (published in 1918) on Canon 1188 concerning oratories, the Rev. P. Chas. Augusting, OSB, DD, writes: "The term oratory occurs in the fourth century and signifies a house of prayer. Later it was restricted to small or private chapels." Later, he expands on this explanation:
"Private or domestic oratories are those erected in private homes for the convenience of a family or private individuals. The term family must here be taken in its strict sense, and excludes artificial persons and corporations. But it includes all the inhabitants of a house living under the authority of the same paterfamilias. Private oratories exist in private homes, which signifies exclusive ownership, so that no public servitude or easement can deprive them of their private character. We find such oratories in the homes of wealthy citizens, in villas, castles, and summer resorts."
Clearly, he is not violating either the letter or the spirit of the law simply because he is maintaining a chapel "of sorts" in his home.
P.S. We should not use the term "home alone" to describe this man. The term has come to mean those who have forsaken all priests as invalid or not lawful and worship must, in principle, be done without clergy and at home. This man is clearly not a "home aloner".