THere is no way that that plant (processor #1) should have been down for more than a few weeks to do the tie-ins...
There are 3 ways to address safety
1) avoid doing the work in the first place 2) engineer the risk out 3) protect the worker (PPE)
If someone wants to argue that processor #1 should be completely shut down for the duratio nof the build on #2, that would be 1 above. Simply not necessary and costly. Are you going to purge all of the fluids out of #1 as well? I think not. It would likely need to be shut down when the tie-ins are done. That is why these things are usually done during regularly scheduled shutdowns (along with other scheduled maintenance). JBII should be running full tilt on #1 and having regular shutdowns for maintenance, tweaking, whatever.
The article talks about 2 above. Various ways that the work can be controlled and monitored. 3 above is the protection the worker wears.
If this job had been done by pros, this article explains how it would have been done.