I don't know about alpha, but I do know my legion discourages alerts for the scenario you mean. One of our guys takes a stronger persons planet they are to expect retaliation/reinvasion. We don't like to see alerts for people when our guy starts things.
I say go for it. Disable, hack, raid... Its all fair to me. I consider the hacking and raiding as compensation for the production you are losing while the other guy has your planet.
Wait for the deflector to time out, wormhole the big gun and take the planet back. And remember... its a game...
_________________Ranks 400+ Join us in exploring..

[20:40] Wredz: just hacked a massive extremely rich minting planet from someone.. thats the best planet i ever hacked
[20:43] DarthFlagitious: is it spearmint or peppermint?