1) it can be blocked anytime, because it doens't
belong to you in a way your own domain / site / server does.
2) Facebook by default is much more oriented to prevent search
engines from crawling its content than encouraging their indexing.
So you won't be able optimize in any form and are actually rowing
against the flow of your "host".
3) If you cause frequent complaints for link spam,
even if outside FB, odds are they are also FB users
and will harrass / report you inside as well.
Conclusion: if you use a FB page as central part of a project, esp. of shady kind (and link spam is shady) you are working on someone else's property, and according to rules that authorize them to take it away anytime.