What you are describing is against the rules as I interpret them. Do not break them or you will be warned and then additional action taken if you continue.
No siege equipment spam
NOT OK: Creating a weapon rack and spawning more than a few items to block movement
Weapons from a weapon rack are fine. Do not create a weapon rack and begin spawning additional construction sites. While the "NOT OK" is phrased "to block movement", it falls under the "No siege equipment spam" rule and the entire thing falls under the 'Use common sense" rule. If you have additional engineers to create the forward base in addition to a weapon rack, that is fine and dandy. But a single engineer having unlimited construction capacity is not.
I may give some leeway due to the wording of the rule to allow 1 construction site to be spawned from the weapon rack for 1 door to be blocked, but it is not there for unlimited spawning of them.
Use the siege equipment, but you need to stay within the guidelines laid out for them. Spawning the throwing lances and tossing them to other thrower teammates is brilliant