I agree with this, but with the important caveat that the trade needs to be on the "wanted list".
The problem is that this process (qualify, who and skilled visa) will take 5-6 years to complete. No one can safely predict which trades will be on the list next year never mind 6 years from now
Dependency is a difficult one to prove, we had to do it as s our daughter turned 18 between doing the medicals and getting the grant (4 weeks). If we had applied a month earlier we would ha e missed a bucket load of annoying paperwork.
Unless you can prove you have been paying for his accomodation (not in the family home) and all his living costs (food, clothing, transport) you will be very unlikely to show dependency so you need to put that aside and start looking for other options, unless a really good agent has some other insights I am pretty sure the dependence route is a non-starter