Your prior post indicated the Russian contractors were prior Russian military who had behavior and conduct issues while in the Russian military. I pointed out that is illogical and possibly irrational.
Besides the fact those types are the least likely to return to military employment it is standard contracting procedure to require discharge papers and service records when applying for such work. The contracting company has no requirement to employ them and will not accept the bad conduct types.
Different contractors has different standards actually.
One thing overlooked is private military is highly illegal in Russia. Wagner is registered on British Virgin Islands if I am not mistaking. Every their employee is by default a felon by the very fact of participating in the group. That is why it mostly attracts people who are already felons.