Nope. previously you were allowed to have multiple accounts in war world, to use as spy's and join other factions, you just weren't allowed them in the same faction.
In regards to survival Cptwin has said "Multi logging itself is fine." Which means we can have multiple accounts, and they can be logged on at the same time. But I'm just wondering if this new rule supersedes that because I know a few players use multiple accounts and have told them that it's fine.
alternate accounts are frowned upon however they are allowed but only in specific situations. for example any situation which would give you an unfair advantage would be not allowed. however for double logging on a pluto world its not a problem. for reference the official rules are posted here: https://www.lolnet.co.nz/viewtopic.php?f=106&t=2676
What about people who don't know how to play skyblocks? can you make use an alt to assist and be a guide since you will loose your island if you leave. Some people do not even know how to play.. such as cobble generator.. I didn't but i picked on fast. I guess i could explain in chat but gets frustrating when they do not understand well and it is faster showing. Lucky I have youtube to help me and minecraft.wiki
i cant see that as being a problem as long as its not used as a means to get 1 off or rare items from doing non repeatable challenges and seeing as your main would be skylord rank it would be pointless to do above.