Hi Sean,
I saw the HoldComplete[ReleaseHold[Hold[... ] construct and the ReleaseHold[...] on the result when executed Michael's code in Mathematica, so I also tried ReleaseHold[...] on the Entity[...] line, but it did not worked. Of course now Activate[...] with the QuantityVariable[Subscript["M", 0],"Magnetization"]] is working and the two outputs are the same, so I can continue with me study of his blog.
Thanks a lot,
János
