SQ and SL are different products, that run in different environments. For instance, SQ can run rules that analyze a whole project to find security issues. This process can takes some time, and requires to have the whole project available for analysis, which are two things that may not be readily available in SL.
It looks natural to me to work on different subsets of rules in those products, as long as the rules present in both subsets produce the same results when run on the same code.