Sure, but the problem is that Aurigny will have to squeeze the capacity currently spread over 11 LGW-slots into the 6 slots it holds. I doubt that the States will buy two or three additional slot pairs for GR (provided that any are on the market at suitable times). The only chance is really to squeeze as much utilization out of the big jet as possible to provide maximum capacity with 6 slot pairs.
It all boils down, however, to the question how many seats the GCI market really needs on a daily basis. If there is a lot of excess capacity on the market with 11 daily flights by two airlines, then there is not too much to worry about other than the usual problems resulting from a monopoly.