Walkers on a team would be unpredictable.
Firstly they would more than likely turn on you.
Secondly, they follow the hoard, so would more thank likely turn on you.
And Infected specialist skill? It sorta defeats the whole point of The Walking Dead. You die, you turn. We are all infected remember. So having a specialist skill would be the same as killing someone, or being bitten by a walker. You might as well call it bleed or burn.
Having said that, turning an opposing team member against their own team via an infection, that wouldn’t be too bad, same as confuse but always the nearest person, and couldn’t be countered…