It can go both ways. The air can just not let the fluid decrease pressure. So when the air gets compressed and then de-pressurizes, the fluid has no where to go because of the air pocket.

I think what he’s trying to say is that because the banjo bolt is leaking, it needs to be replaced but because the bleeder bolt is stripped he won’t be able to get the air out and is recommending to replace the caliper

The bolt that holds your brake fluid line onto the caliper is stripped out and bleeding fluid , the easiest way to fix it is to replace all which might include the brake line at worst case , no matter what your looking at a caliper which should come with a new banjo bolt and a fluid brake bleed job