Russian concerns aside, why is the USN concerned with fighting forest fires?
Absence of evidence is not evidence of absence.
I smell a conspiracy theory in it's incipient stage... You see (ahem) since the Admiralty Court has jurisdiction over all navigable waterways, and the definition of 'navigable' has been stretched to include just about any running water, the Navy has laid claim to pretty much all of America's watersheds, which are usually located in forests (cut me some slack here). Since the forests are therefore in the Navy's jurisdiction, it stands to reason that they're involved in fighting forest fires, and would purchase Russian aircraft for that purpose.
This also means that any running water in your house makes it Navy property - which is why I haven't taken a shower in over 15 years, and have yet to succumb to the government's secret 'mind control through fluoridation' scheme.
Reading the article indicates that is not their concern.
"Moreover, the hovercraft's special coating enhances lift by 40 percent (with the help of turbulence flows). Consequently, the EKIP's payload accounts for only 40-45 percent of its mass; meanwhile the relevant aircraft ratio is 20-25 percent"