StrongLifts 5x5 off-day question

I'm new here, sorry if this is the wrong place to post, but I have a quick question that I'm sure could be answered quickly.

I know how the program works, but I have a question about the off days. If I do a 3x split for weight lifting, and do cardio on my off days, 2-3x week (depending on my schedule), would it be helpful or harmful if I added a light ab/core exercise on my cardio days?

Eg. a low intensity core circuit (3 sets) like 15-20 crunches, 30s-1m plank and medicine ball twisting crunches.