If you've got the alt advantage, stay up there, call over on VOX to ask if he needs help or wants you to make a pass to make the bad guy break.... and if not, keep an eye out for the next enemy con coming for a pick.
If co-alt, again ask if he needs help.
If in a populated, but less than crowded furball sky, wing up. Ask if he needs help. Cover his six against the next enemy if you are not too worried about your own score, or move on to other enemies if you are more into the solo thing.
Personally, I don't have much problem if someone can get into a position to take a shot on one I'm following, especially if defending or attacking a field.
For my part, I'll take a pilot's wing to watch his six vs another enemy when he is busy engaged with one. I won't take the shot unless he shakes the friendly and does a lovely spread eagle silhouette 100 off my nose. If there are two or more in a pursuit conga line, I'll break off and look for other prey unless I'm the lead and real close to a firing position.
In the end, listen to your own conscience. I don't need name in lights or a low score to have fun in a game. I also don't need to get worked up over some of the antics some pilots display in the game. I don't find enjoyment in trying to game the game or stealing kills from others. I don't get off in taunting over PM or Ch200.
To each his own. It's an online game. You'll see all sorts.