Though, the official EF rules does suggest that your private room is exempt from this rule/ban, by contrast implying that it is allowed. Especially since this is under the "Hotel Rules" section, which one would assume should mirror the policies agreed upon together with the hotel.
Also, whilst it might be implied, there's also little to no part of the RoC that refers you to the hotel's policies and that tells you to follow them in the case of a conflict like this.
And to even further this; Anyone who has NOT directly booked a room at the hotel (by being someone else' roommate and thus not the one booking the room) has NOT received a copy of the hotel terms unless forwarded by the room owner, thus leading to the convention RoC being the only such they've been made aware of. Unless they specifically been told by someone else or specifically went searching themselves for it on the hotel website.
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Either way around, it feels very misleading and could potentially even be considered a breach of contract by certain European jurisdictions (if it's not already covered by EU contract law).
To summarize, the rules seem maybe too specific about your private room being an exception to the rule (implying the opposite to be through, based on the wording) but does not specify at all that the hotel's own rules apply over EF's in situations like these. Perhaps also can be good to include a link to the hotel's rules?
ALSO, to clarify, I don't mean to complain; Just my feedback on the manner for what I personally feel may need rewording/changing.