Because of the different indexing rules used , it is quite common , and normal, to find differences between the index on FreeBMD and that on GRO.
The first thing to check is whether other entries on the same page (7a 144) are in the GRO index - and in this case they are, so it isn't a case where the whole page has been missed during the digitisation process, which is seen as an issue sometimes - it could just be that one entry was missed, but that is unusual.
The most likely explanation is that the entry has been transcribed and indexed in a different name, or name variation, but because of the way the GRO search engine is locked down they can be very difficult to find.
But I can't find him.