The T-14A Heavy Tank was technology from Australasia 20 years ago, and Arthur was not worried that the Russians would catch up to Australasia through such tank technology.
Moreover, to be honest, Russia's own tank technology was quite good, and they were fully capable of developing simple tanks like the T-14A Heavy Tank.
It would be better to sell the blueprints to Russia, earning some funds and minerals from Russia, allowing this tank technology, already 20 years outdated, to finally play out its remaining value.
This would also comply with what was mentioned in the United Nations Declaration, that all signatory nations should commit all their manpower, financial and material resources to address this war.
In simple terms, by selling tanks and technical blueprints, Australasia could also increase its contribution to this war.
Even if the Russians achieved some military success with these tanks, Australasia, having sold the tanks to Russia, would also share in the contribution.