How do you propose the Chinese or Russians will get there in large numbers, with lots of military kit, and not be detected?
They need to stage personnel and kit for transport. Then they have to cross vast expanses on ocean and airspace that are monitored, imperfectly, but still monitored.
What you are proposing is so outside plausible that it isn't worth spending billions of dollars on. We would be better served by spending those billions on improving airfields that already exist in the Arctic, and buying more aircraft and BV type vehicles to patrol with.
The more reasonable and likely reason to buy a large icebreaker with large helo capacity is for disaster relief/rescue, and supporting CA sovereignty operations in the Arctic. When an explorer cruise ship breaks down and runs aground off Baffin Island, having a big ship with lots of space for people and helos would be handy.