Has anyone heard of this? My brother in law just had his kitchen
remodeled and the contractor that installed the porcelain tile floor
actually mixed the sealer into the grout then applied the grout.

Yeah. It's like the stuff they put in concrete so you don't need wire or
rebar reinforcement in the slab. In other words, a phony shortcut for the
contractor with a make-believe story for the homeowner.

Did you also fall for the self-tuning piano at the music shop?