[singular]

Yes, you're right, other than the idea that the job posting isn't entering into an argument - I'd say that it is, the person is taking a position that they feel this is a reasonable and justifiable job to advertise.

We can reasonably consider this implicit position and draw conclusions, and yes absolutely, because something happens to be a personal attack, it isn't necessarily ad hominem. Saying 'ignore what this person has done and listen to me telling you he's a great guy' very much is.