I wouldn't recommend standing on porcelain slabs

Why ask here instead of discussing with your installer/seller?

A properly installed top should support the weight of an electrician easily, but there are other possible reasons for the failure. It's doubtful it will get worse, but short of coaxing some super glue into the crack to stop contamination, there is no fix.

That propensity to crack is why most experienced designers and contractors do not recommend porcelain. Look underneath the counter, and see if it is fully contacting the cabinets. If it is not, it should be fully shimmed in multiple spots. Even if it's fully supported, it still has internal bound stress that a glancing blow can release as a crack. In other words, it can crack from cause, or absoltuely no cause.

The electrician stood on it? Seriously?

Edge Chipping: High density makes edges brittle and prone to chipping under heavy impact.