Swapping shifts with a secular person on Shabbat

Rabbi, as someone who comes from the world of high-tech, this practice is common in all companies. It is known that there are standbys on Shabbat because the product needs 24/7 availability that requires maintenance when there are urgent problems (such as those that cannot be delayed).
At the company I worked for in the first place, they structured the standby schedule so that the religious did not receive standbys from Friday noon until Saturday afternoon. As a result, a person who does not observe Shabbat was on standby during these hours.
By the way, there are standbys on Yom Kippur as well.

In my humble opinion, the rabbi misread the question. He does not commit the desecration himself.
A comma should be added to understand:

“They are asking me to find a replacement for Shabbats(,) where I am unavailable”.
That is, not that on some Shabbats he is available and on some he is not, but on all Shabbats he is unavailable.

It doesn't matter. When you're looking for a replacement, it means that in principle you work on Saturdays and the replacement is yours. If the company keeps people on Saturdays and you only get work on weekdays, that's a different matter.