Multiple accounts for opening purposes

I have read the Terms of Service and it said that making multiple accounts is allowed to hide opening preparation or playing with self-imposed impairment. Does that include playing questionable openings?

Sure.
You can have another account for questionable openings, but please, if you play way below your level there, do not mix playing on that account with playing "normally".
Example: berserk account, blindfold account, or, to answer your question, an account for trolling openings - such as bongcloud-account :-)

I think the point of the rule is for people not to open up an excessive number of accounts. If you want two accounts there really isn't anything stopping you from doing that.

For exemp if you habe a normal account, a berserk account and a blindfold account it is ok, because they are different. Three normal accounts are not needed so it is not ok.
E.G i had an blindfold account(did not want it anymore so i closed it) and I have an normal account. That is allowed