Complete nonsense, its like there's no concept of digging in and defending for the Russians.
The moment the decision was made that the offense will be in the east the south should have immediately assumed defensive posture. Dug in, trenches, there should have been 10 pontoon bridges, 5 for use, 5 for backup and another 5 in reserve held near the banks to quickly reinforce. A fleet of excavators and bulldozers to make semi-temporary dirt and gravel roads to said pontoons.
What were the Russians in the south doing all this time?
10 bridges? Have you seen the width of the channel? For the number you mentioned, at least something like +30 engineering vehicles are needed just to keep the 5 floating bridges operational, not to mention the vehicles needed to support the 5 backup bridges and the other 5 bridges in reserve, considering the length of the MTU-72(MLC-50).
Another thing, how will they assume a defensive posture to maintain positions on the right bank with only a limited beachhead in Kherson and with much lower numbers in addition to being under pressure against the Ukrainian advance? If the Russians still had the bridges intact, not depending on engineering vehicles and far from the range of AFU artillery and also Ukrainian air power, it would make sense to do that and you would be right.
You are confusing everything. What did you say here:
Dug in, trenches, there should have been 10 pontoon bridges, 5 for use, 5 for backup and another 5 in reserve held near the banks to quickly reinforce.
The Russians did not create a defensive posture to maintain positions on Kherson. This is not a defensive posture to maintain positions in order to reinforce the fronts, but to create a defensive retrograde posture. On Telegram, it's pretty clear that if they could, they could maintain this position on the right bank, but with limited supplies leading to heavy casualties, which is quite believable.
The delaying action is conducted to exchange space for time. Thus, it is carried out in such a way as to allow the majority of troops to retreat in an orderly and rapid manner through the watercourse. It can be conducted continuously, in successive positions towards the rear or in alternating positions, depending on the type of forces employed. The value of the force that performs the delaying action is a function of the enemy and the time needed to organize and establish the defense on the other bank and the time needed to prepare the crossing area. It takes much more than bridges to do this, it needs engineering reinforcements, anti-aircraft artillery, barrier system, field artillery... if retrograde action is desired for a long period and the enemy strength is much superior.
Another thing to consider. Will the Ukrainians really let the Russians retreat that easily? Hitting their ferries and pontoon bridges would be catastrophic.
It would be downright stupid for the AFU to let the Russians do that, even more so when the crossing forces at Kherson are within range of the Ukrainian artillery and air force as well. A retreating transposition combines two of the most difficult types
of operations - a retrograde movement and a watercourse transposition. Ukraine will have to rely on air assets combined with artillery power to create chaos on the river crossing at Kherson, even more so when this evacuation will be under concentration of the crossing forces, which increases the chances of tactical success by potentially neutralizing many troops under a strong concentration of localized firepower. If they cannot effectively suppress Russian artillery on the other side of the shore, they can simply direct their artillery towards the Russian forces acting on the front line that are providing cover for the crossing, that is, directing fire not only at the marching columns, as well as for crossing places, especially during their use.