It's only for a Tier 2 application, I believe. Once someone has a Tier 1 or other visa they can work on (i.e. spousal visa, dependent visa) they should have the same chance at a job as everyone else - as they already have permission to work in the UK.
In terms of costs for Tier 2 sponsorship, small companies have to pay £300 for a licence, but it will cost large companies £1,000. Once they have a licence, it will then cost them a further £170 for a certificate of sponsorship in order to be able to employ an overseas citizen. If the person already has permission to work in the UK, they will not have to pay these fees in order to employ them.
A friend of mine (American citizen) interviewed for a job in England, but was told that while they were willing to employ her, the company couldn't afford to become a Tier 2 sponsor and so she could only have the job if she got herself other permission to work in the UK (i.e. a Tier 1 visa). Unfortunately, she doesn't currently qualify for Tier 1 (and may never qualify if her masters degree is given 0 points), so she is stuck in the US for now.
If he is going to come over to the UK as your Tier 1 dependent then that would be the easiest way for him to find employment. Also, his dependent visa will be tied to yours and he would also be free to apply for almost any job he likes, but a Tier 2 visa is tied to the company and that particular job, so if he lost his job, he would either have to go through the visa process again and get a new Tier 2 visa or return to live in his home country.
