Cloud in this case appears to mean "Microsoft hosted datacenter".
RPC-over-HTTP has been around for awhile now and should work fine with this 'cloud' service. They didn't seem to imply the Office apps were going cloud, just server side.
Ask them to talk about the mistakes they've made or project failures they've been a part of.
If they claim it's never happened, or it wasn't their fault, etc, then they probably are lying or stupid.
If they can explain the failure, why it happened and how they've avoided the same thing in subsequent projects you've probably got a good one.
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