Don't worry, Kari doesn't wear shoes
Yeah, I didn't think of that, but they could have some shuttles, armed with guns, hit them on a run from behind. Personally, I would have made sure that some of those shuttles carried equipment to setup some planetary lasers or missiles to fire into space from the planet surface.
If I were the Scarborough, I'd probably be zooming in at top speed, head on at a cruiser, fire off some shots and break away with the momentum carrying me off before they can fire anything heavy in my direction. Probably attract some fighters. The Cirin fighters were no problem for the old Niobe, but the Darani fighters generally seem to be better equipped (with cap buster missiles to boot) and I'd say the UTC fighters are probably a lot more nasty. But then I doubt the fighters would waste their cap busters or any decent amount of time on a civilian cruiser when there are bigger fish to fry and deal with.
In the end, the Scar will be mostly an annoyance as long as it keeps making quick sweeps on the outskirts of the battle field, so I can't imagine anything really deciding to take her on, except for a fighter squadron.
Another part of me is wondering if Novosi is really wrong about how many mercs will turn up to the fight considering the many sympathisers to the Cirin Alliance. Maybe the Niobids aren't the odd ones out, but then again, they probably have the most powerful ship of anyone, so its less of a risk or futile gesture for them to make. Really though, the Merc fleet could still be a serious nuisance to the enemy fighters who'd need to pay some attention to them, not to mention any hits they can put on the engines of the caps if they get around them. Its more targets for the Daranir and UTC to deal with and there are already to omany.