I have no idea whether forming an U18 national team as an entry to the MHL would stop or even slow down the flow of the best prospects lining up at the airport to get to Kootenay or Sault Ste. Marie as fast as possible. Last year, 49 Russian kids played in the CHL, and next year, the total is expected to be around 64. Those aren't just 64 kids, those are the 64 BEST KIDS! But they won't be the 64 best for long. The vast majority were a work in progress when they left, and their growth will stop after a couple of years in a hockey style and culture that is totally alien to them, where they are isolated by inability to speak the language, and where they will ultimately quit hockey by their 20th birthday.
Russia gets nothing out of this flow to the CHL. After 7 or more years of all of the talent flowing out to the CHL, the 2015 WJC team was still predominantly kids from Russian teams, and there were only 2 CHL-based players - Barbashev and Tolchinsky - who contributed to the team. Surely the CHL/NHL brass must wonder whether the huge influx of Russian refugees is working tot their benefit, but the RHF certainly knows that it sure as hell doesn't help Russia.
So they have got to try something to convince the kids to stay home. And they can't wait until Russia has completed its journey down the road to end all corruption. The best leverage the RHF has now, IMO, is access to national teams. Participating in national teams is what separates top prospects from merely being good prospects. It is what makes their name known, and marketable. Their financial and job security future is heavily impacted by the ability to be a "world class" player. If you are not world class, then you will be required to work for less money and less security. So access to the NT is critical to those who have dreams of big things for themselves!
I don't know if a NDP is a great idea of not, but separating the top U18 prospects and assigning to an NT doesn't prevent any other prospect from playing in the MHL, or even the CHL, if they choose. But if they go to the CHL, they can't play on the U18 team, and unless they are really successful and develop in the CHL, they won't be on the U20 team either.