Your interpretation may be technically correct, in that they (A
BYC) are not issuing a flat prohibition against check valves in bilge
ie: “H-22.8.9 A check valve may be used only when necessary to prevent an automatic bilge pump from cycling on and off*
due to back flow from the discharge line.”
*This would not include annoying back flows that don’t cycle the pump ‘on’.
Check valves are notorious for failing in both the open and the closed position, which respectively leads to flooding or failure to pump.
When used to prevent backflow pump cycling (as permitted above), ensure that the check valve is not too close to the pump.
If the valve is too (particularly in longer discharge runs) close to the pump, the pump may not be able to overcome the weight of the water on the discharge side of the valve, rendering the pump ineffective/inoperable.
See the Rule
Instructions, for instance, which specify a Vented Loop, and NO Check Valves.
Here ➥ http://www.rule-industries.com/files/itemdoct6041.pdf