Mantis are smart. I struggled to evict mine from its rock too. Took several frustrating nights for me... Until one day I managed to positively ID which rock it was hiding in, then took it out quickly. Practically snatched the rock outta of the water before it had a chance to run out.
Leaving it in air for 20min did nothing for the shrimp, they don't evac the rock like crabs do. I finally managed to drive it out with fresh water that was slightly colder than room temp.. Now it's got a home of its own in a small tank
if you still want to try bottle trap, most of the traps I have seen online are transparent bottles. More inconspicuous, maybe doesn't matter but worth a shot IMO if your current one is not working. Read that they are capable of learning too - meaning if your bait is gone from trap, but no shrimp, means it's figured out how to get in & out. Need to change trap design. All the best bro....
Btw pls be safe when handling them, yours look quite big(about 3-5cm?), probably capable of doing some harm if it gets close to your fingers!
Your PO4 is high at .25, target is 0 or .03. Considered dosing goodbyePO4? Henry there have.