Sounds reasonable, but there could be something more under the hood.
I find this cryptic: “feature will roll out progressively”, plus talk about calibration and algorithm.
It seems that DxO has realized that and in PL9 the default LSO Intensity of 100 corresponds to PL8 Intensity 0.0, while PL8 default +1.0 corresponds to PL9 value 133.3. For portraits you may like still lower values, but for very noisy DP photos taken with soft lenses the old default might work. I had few cases where PL8 LSO +2.0 was just right. On the other hand, with Plena lens (Nikkor Z 135/1.8) I quite often disable LSO.
Here is how PL9 maps LSO Intensity when dealing with PL8 dop files (based on my test with PL8.8 and PL9.0.1 trial) :
PL8 PL9
-3.00 15
-2.50 29
-2.00 43
-1.50 57
-1.00 72
-0.50 86
0.00 100
+0.50 117
+1.00 133
+1.50 150
+2.00 167
+2.50 183
+3.00 200
It’s linear in the [-3.0..0.0] and [0.0..+3.0] ranges, with slightly different angles.