With respect, you are directly contradicting yourself.
On the one hand you say:
History tells us that it would only be a matter of time before FlyBE sold its slots to the highest bidder
and on the other hand you say:
A single commercial operator would also mean fares likely to go through the roof before very long
How could any operator who doesn't own slots charge excessive fares?!
The real issue here seems to be that the States need to ensure Guernsey remains a destination that any airline wants to serve. Flybe saying that they're bringing in their first E175 to Guernsey suggests a) that it is high on the list of their most valuable destinations and b) the States have lobbied BE hard to make that happen.