Got a mail back today from a helpful information chap in the Port and it turns out that there is now a 7 days per week "fietsbus" service which uses the tunnels underneath the Schelde and under the Kanaaldock (the latter replacing the Lillo Brug route-wise. He said the bridge is now only for trains, so maybe someone has done a risk assessment and decided it's not good to have bike down in when the trains are coming?