Yes, you can buy or sell any US exchange-listed security on LTSE starting today. If you check the market share tracker at CBOE you can see the "notional dollar value" of the shares which have transacted on the platform today: https://markets.cboe.com/us/equities/market_share/
It's clearly not zero, so somebody sees some benefit in it. So I don't see the issue with saying that we are "open for business"
I think GP's point is that you're saying "we're open for business", but the LTSE isn't offering people who buy stocks any added value yet.