What happened to Reginald Cooper?

When I located grandmother, Gertrude Georgina Cooper, in the 1901 census for the United Kingdom I discovered something that I had not been aware: my grandmother had a younger brother, Reginald. At least there was a 3 month old male listed in the household as the son of John Cooper. I mentioned this discovery to some of my aunts and they were unaware of this uncle. The family emigrated to Canada in the early 1900s and in the 1911 census for Canada, I found my grandmother as the only child still living with the parents in Mimico (part of the Toronto area). Her older siblings were married and living elsewhere. I have found the ship manifast of when the John Cooper left the UK for Canada (in August 1902) as well as the manifast for their arrival at Quebec City, with destination of Toronto. (Actually the oldest son, Albert, didn't travel with the family, but I found a manifast for when he arrived at Ellis Island just months after the 1901 UK census.) So who is this Reginald? Why was he not with the family when they emigrated to Canada? Was he left behind for some reason? The 1901 census had also listed John Cooper's family living in the household and he didn't emigrate. Or had Reginald died? Online records for births in the UK only seem to be indexes with very minimal information. And unfortuantely, for me, both 'Reginald' and 'Cooper' are common names. However, upon closer examination of the birth and death indexes jointly, there was a 'Reginald George Cooper' birth registered in Monmouthshire during the first quarter of 1901 and a death for a 1 year old 'Reginald George Cooper' was registered in the first quarter of 1902, also in Monmouthshire. Is it safe to assume that the two entries are for the same person? And more importantly, this infant was my grandmother's brother? The timing would fit as the death was months before the family left for Canada. Was that a deciding factor for the relocation? I have never heard what prompted the family to move from Blaenavon Wales to Mimico Ontario. I have not been able to associate 'George' with other family members, except for my grandmother's middle name being 'Georgina'. But maybe the name has nothing to do with other family members and was a trendy name at the time.