It's genius, really: trying to buy $200M of coins directly would spike the price before you actually gained ownership of the assets, so you'd get stuck buying in at a high price. Instead, they're going to keep all of the coins they're mining, which indirectly raises the price on assets they essentially have already paid for - those coins aren't being released into the wild like they would by a company like AM, so Joe Lewis is relieving the inflationary pressure of mining, which will manifest as an increase in value on his newly minted coins.
So, Joe mines coins via Avalon and puts those in a private wallet somewhere. And even though the rest of the Bitcoin community sees those coins getting mined and knows exactly where they are, it "relieves the inflationary pressure", which I take to mean that the value of the rest of the BTCs out there go up? I don't see how or why - we will all know that those coins exist and are available to be circulated at any time, so you can't price the remaining BTC's as is they're off the market (ie destroyed).
Inflation isn't some magical thing that happens because everyone looks around at how many Bitcoins there are. It's a supply/demand problem. If more people are looking to sell (or use) Bitcoins than are willing to buy (or accept) them at their current price level, the price level of BTC necessarily decreases (and the price level of everything else necessarily increases relative to BTC).
Normally you have miners selling their mined BTC to cover fiat costs: hardware, rent, electricity, etc. That is supply-side pressure, or inflationary pressure, which would be relieved if someone like Joe was bankrolling the whole thing in order to get coins in the first place.
He's not, though (unless he's lying to preserve his interests), so the point is moot.