Transports and submarines in the same seazone

[Simon98v]

From the rulebook about submarines:

Does Not Block Enemy Movement: The “stealth” ability of submarines also allows enemy ships to ignore their presence.
Any sea zone that contains only enemy submarines does not stop the movement of a sea unit. Sea units ending their combat
movement in a sea zone containing only enemy submarines may choose to attack them or not. Sea units can also end their
noncombat movement in a sea zone containing only enemy submarines.

About transports

Any sea zone that contains only enemy transports doesn’t stop the movement of a sea
unit. Air or sea units (other than transports) ending their combat movement in a sea zone containing only enemy transports
automatically destroy those transports (unless they are ignoring them to support an amphibious assault instead). This counts
as a sea combat for those sea units. Sea units can also end their noncombat movement in a sea zone containing only enemy
transports.

If I interpreted this correctly, a seazone containing both submarines AND transports blocks the movement of sea units. This doesn´t make any sense.

Do submarines have the ability to protect allied transports? (obviously not from air units) Can you ignore making an attack on a seazone containing transports and submarines to make a seashore bombardment?

[Panther]

@Simon98v:

…

If I interpreted this correctly, a seazone containing both submarines AND transports blocks the movement of sea units. This doesn�t make any sense.

Do submarines have the ability to protect allied transports? (obviously not from air units)

Can you ignore making an attack on a seazone containing transports and submarines to make a seashore bombardment?

Don’t forget:

@rulebook:

An enemy submarine and/or transport does not block any of your units’ movement, nor does it prevent loading or offloading
in that sea zone (with one exception - see Special Combat Movement: Transports, pg. 13). As the moving player, you have the
option of attacking an enemy submarine and/or transport that shares a sea zone with you. However, if a warship chooses to sink
an unescorted transport, that warship must end its movement in that sea zone. It is possible that some units may stop to attack
while others continue moving through the sea zone.

This should answer all your questions.