The argument over what does and does not constitute spawn-killing has been raging as long as there's been Dogfight. I wish I had a buck for every time I've been blitzed with my wheels down in service of some otherwise presumably respectable player protecting his/her zep.
The difference between spawn-killing and suppression is entirely subjective. The only things easily agreed upon are that killing spawning planes from a tank (under any circumstances) and killing spawning planes with no incoming bombers are unacceptable. Still, even the latter is subject to debate. How "incoming" does a bomber need to be to qualify? Within sight of the enemy base/carrier? Less than halfway across the map? Simply in the air and pointed in the general direction? It seems easy enough to agree that camping (or "base suppression", if you prefer) and spawn-killing are two decidedly different things. Hold the base for your teammates by holding reds at the base but at least let them get airborne. As common-sense as that might seem, ask ten players and you'll get ten different opinions. Ask ten Mods and you might get five.
In my view, for what my view is worth, it boils down to a question of common courtesy. If all you're in it for is to kill, rack up points, win...then you'll adhere to the loosest interpretation of what acceptable spawn-killing (base suppression) is. If you're here to earn respect, make friends, have fun and establish a lengthy "career" as a player you'll give a little more thought to how your particular suppression tactic might be received, and how it might follow you through the game over time.
--w--