The strength training workouts are put on swim days because your bike days will eventually have a brick included and some run days will have an extra spin for more saddle time. So it’s just for ease of scheduling and hopefully getting in a routine. However, strength training can be done any day of the week. It just needs to happen.
I offered my recommendation to do the strength training as an extension of your bike and run workouts in hopes that they are more likely to happen. Again, they just need to happen, whenever, however.