The reason for not running MANLGW was always that the limited slots and aircraft could be more profitably used elsewhere, not that there wasn’t any demand for it as a connection feeder. In this context it’s not massively surprising that it would return at a time when other routes will be thinly operated.
BA have also take a large sum of money from LGW to promote their routes from Crawley International, so I would be astonished if at least those routes didn’t make the trek back from Heathrow next year.
And yes, showing utilisation won’t hurt in the fight to block Wizz.