Your argument seems to have the assumption that sitting Lauri comes at no cost. Maybe that's the case. But it might not be. There are several ways I could imagine that sitting Lauri comes at a cost (or that him playing provides value). But I don't think any of us know what is at play (or have any way to estimate what the Jazz see as the value of Lauri playing).
As for the rest of the argument, I understand the point and I don't begrudge it. But I just don't see the value in "winning" the tank race. We're in a position where we're giving ourselves every chance to do well. And we're very unlikely to fall from that position. If 5th through 7th matters that much to you, have at it. I doesn't to me.
There may be a conversation to be had about the indirect consequences, but I haven't heard an argument for the cost of sitting Lauri. What's certain is there is a non zero benefit for the L, no benefit for the W. Personally, I find that the indirect consequences are heavily in favor of tanking especially if you believe in playing time as a developmental resource. For me, the right amount of remaining games for Lauri to play might not be zero, but it's not far from it.
The value is pretty simple, you get more expected utility from the draft. How much that is, like I said it's subjective. Well, the actually odds are not, but the importance of those differences is. I find it hard to argue that having the difference between 5th and 7th best odds is not more meaningful than winning the 26th most games instead of 24th most wins.
It's kind of like tossing up a heave at the end of a quarter. Very little value in that shot and even if it goes in it does not necessarily mean it will change the outcome of the game. But you really should toss up the heave instead of letting the clock expire.