Learn English – Plural of composite noun

The first sentence features ellipsis, that is, the omission of elements which are recoverable from the linguistic context or the situation. A full version would be on both the sender side and the receiver side. Once we reach the end of the sentence we can recover side and place it in our minds after sender. That’s not too difficult to do because the missing element occurs within a few words. However, some readers might be uncomfortable in performing that little bit of linguistic gymnastics, and that is presumably what the reviewer felt.

The answer to your question is that both sentences are grammatical, and both convey the same meaning. If you think your readers might have difficulty with the omission of side after sender, then use the version that uses the plural: on both the sender and the receiver sides. Alternatively, use the full version of the ellipted form with the singular: on both the sender side and the receiver side.

I believe that strategy would generally be referred to as "delaying tactics".

Some comments mentioned "running out the clock", which is a sports metaphor from timed sports. I've heard it used as a metaphor in other arenas, although its most applicable when you know exactly how long you need to delay.

In the work arena specifically, there is a tactic called work-to-rule, where the employee gums up the works by following every single workplace rule to the letter.