What do you mean by having high single time makes you ineligible for some operators?
I've also heard of this, but unsure of what the upper single engine time limits are
It's usually operators with twins who deem your experience as a threat, especially so with SE Turbine time. What it means to them is that you are only good for a few hundred hours as the combined SE turbine and twin time ticks all the boxes for regionals, so you will probably be out of there ASAP.