Good job. Sesami is clearly a B2B e-procurement marketplace that aggregates a diverse pool of suppliers so that it can match make them to buyers' RFQs.
Intermediary-oriented markets can provide facilities to make it easier for buyers or sellers. The RFP tool is tailored to support buyers, but it doesn't mean that the platform is a "buyer-oriented" market. You need to understand exactly who owns the market to qualify it as buyer-, supplier- or intermediary oriented.
Also, G2B is just a subclass of B2B. In general, it is sufficient for you to distinguish between selling to consumers and selling to businesses. No need for any further classification.
Hope this helps.