(Note: I'm not very knowledgeable about this period in Russia. I'm piecing this together from a few sources.)
Somov's regiment was not sent due to the Napoleonic threat, but was part of the existing task of defending the enormous and sparsely populated Russian frontier.
In the larger context of the Russian Empire in 1800 this makes more sense. Russia is very large and had threats on all sides: "Tartar, Turk, Pole, Prussian and Swede" and now the French. Transporting an army in 1800 was very slow, mobilization could take months. Russia was too large to have a centrally located "reaction force" to respond to crisis. They had to have units in prepared positions near every potential hot spot to slow an invasion, or react to a raid, or put down a rebellion.
While they faced large, traditional, concentrated Western armies on in the West, in the east and south they faced disbursed raiding parties of Turks and Tartars. The southern and eastern fronts of Russia in 1800 were more like the frontier armies of the United States than the armies of Napoleon. They filled many governmental roles in sparsely populated areas: military garrison, police, civil engineers, and labor force.
To deal with this, Peter the Great instituted large standing armies and deployed them to potential trouble spots. Supplying and concentrating them across such large distances, and such sparsely populated land particularly in the east, was difficult. Catherine the Great dealt with this by creating a Military Commission who created administrative divisions close to the areas being defended. A large mass of troops was garrisoned in Moscow, centrally located on the Russian transport system, to quickly (for the time) reinforce hot spots. Tsar Paul further organized divisions into "Inspectorates" to deal with corruption. The divisions would now be overseen by inspectors reporting directly to the Tsar.
"Somov's Regiment" raised and sent one or two battalions to Kamchatka for what became the Kamchatskii Garnizonnyi batalion (Kamchatka Garrison Battalion). This was part of the larger Siberia Inspectorate of about 10 battalions in 1796. It was assigned certain hamlets, "cantons", which they defended, aided, and relied upon. Soldiers would help with the labor and farming in exchange for supplies and shelter. In addition, the regimental commander acted as a military government, parallel to the civilian one, within their territory.