Glenn, thanks for the reply,
Let me clarify. The blocks removed would be below grade. He wants access to the soil underneath of the slab porches. He wants to probe along the outside of the foundation and the underneath of the slab porches from this access point and apply pesticide. He then wants to leave the block removed for future inspection access.
He keeps telling me this is a better way than drilling the slab porch. He claims its common. He also says it is a lot more work to do it this way, and if I insist on him drilling instead he will do that, but there is no guarantee that he will get a full termite barrier with drilling where as if he knocks out a few blocks he can get a continious wrap of termaticide around the foundation. He only needs to do this in 3 places, front porch which is earth filled well above grade and the two back porches which are poured concrete at grade level. The rest of the foundation will be trenched treated and filled.
My concerns are excess moisture esp after a heavy rain, structure integrity, etc. I am okay with the front porch, its the back patios where the blocks he wants to knock out are below ground level.