This seemed like marketing speak to me so I went looking for research on it. I found something which was interesting:

For instance, the addition of Sc and Zr to 6061 alloy shows a slower ageing response at 190 °C, resulting in lower yield strength of 321 MPa (aged for 5 h) than base 6061 alloys (350 MPa) [64]. On prolonged ageing (36 h), a significant drop (~ 19%) in the yield strength of 6061 alloys was reported compared to only a ~ 6% drop in ScZr-modified 6061 alloys. [1]

I wonder if I am reading this right or if 6061 is actually not very alloyable with scandium.

https://link.springer.com/article/10.1007/s12666-022-02547-z