I've been doing that for a while and to me, I feel safer using this method than using a brush. My dexterity isn't what it used to be. Lowering a stylus into Blu-Tack may also be easier on the suspension of delicate moving coil cartridges than running a brush under the stylus.
I had that in Discwasher kit from back in the 80s. The whole thing may have cost $24, and included the record cleaner, stylus brush, fluids for both, the Zerostat, a neon bulb to test the Zerostat with, a brush to clean the record cleaner, and a wood base with a smoked plastic cover. Nowadays the Zerostat alone is $$$. Still amazes me how cheap those used to be.