There are many threads on here about that self same topic. With just a copy of the article you supplied, I can't check to see if this person is basing their opinion on just one study; if so; that is a serious short-coming.
The vast majority of the studies do not include toy breed dogs, but more the medium to large sized dogs; and how, when, and if, those results can be attributed across all breeds of dogs is un-known to many.
Behavioural risks or benefits is one area that many studies bring up conflicting results. So imo, the science is not there yet with any degree of accuracy. In point of fact the science is not truly there yet for any breed of dog, although there are some very concerning results for some breeds of dogs - but not so much toy breeds and in specific the Yorkshire Terrier.
I will link you to a thread that actually links to real studies, the thread is quite long, with many contentious parts to it.
http://www.yorkietalk.com/forums/gen...n-if-ever.html
You can read up on the research yourself, and have a conversation with your vet about the benefits . risks
for your specific dog prior to making the decision to neuter him or not. It is very wise to have pre-op blood work done prior to any surgery.
You can also elect to wait to neuter until after 8months old, which should mean that the boney growth plates have closed and thereby reducing or eliminating the osteo risks of early neutering. Again imo.
Good luck with your decision, and do remember to have a conversation with your vet about this.