No, it isn't. The whole point of antibiotics for IBS treatment is that you already have an overgrowth, and you want to disrupt that and level the playing field.

This is literally the reason I've been on short course antibiotics (<1 week or a single 4 tab dose) at different points, because it eliminates the constant bloating and gives probiotics a chance to work.

The exact reason why overgrowth happens is because an opportunistic strain takes advantage of a dysbiotic state - even if you suppress it with antibiotics, your gut still lacks the robustness of composition necessary to be resilient. In fact, no antibiotic is selective enough to not impoverish your microbiome.

Probiotics might help, but a few or a few dozen non-gut-sourced strains simply cannot compare to the hundreds present in healthy stool. The effects on microbiota-dependent conditions are often weak to none.