The VWB puts out a lot of questionable advice.
People who like to foil usually won't wrap till internal temp hits the 160 area, then won't pull meat off cooker till it hits 195-205. Every pig is different and a picnic roast will be probe tender "done" at different temps. This means "never go by internal temp to decide when to pull a picnic or butt".
Keep it simple and don't open up the cooker till it's getting close to "done". The best way to know it's "done" is the poke, probe, or bone wiggle test.
It seems they like to make a very simple process very complicated.
Get the cooker stable at desired cooking temp. Look for thin blue to invisible smoke before tossing on meat. If the cooker is pumping out a bunch of white poofy smoke, it's not burning cleanly, and will deposit a bunch of nasty creosote on the meat. Google "minion method in a weber smokey mountain" That will give you good advice on how to properly start your awesome bullet smoker.
On the sop/spritz/mop. Don't even bother, all that does is extend cooking times and remove the naturally moist cooking environment created by a WSM. Leave the cooker closed, don't mop, spritz, foil or peek. You'll know when it's getting done by the sound the meat is making. Loud sizzling means it's in middle of the stall, as the sizzling subsides, it's almost done. That is the first time to peek, and check for "done".
Picnic roasts have so much internal fat and moisture, there is no need to add any to your cook. Keep 'er closed up and let the magic happen.
When a picnic or butt is "done", I like to wrap in foil and old clean bath towels and toss in an ice chest for a minimum of 2 hours. It allows the pressure to stabilize and the juices to redistribute throughout the meat. They can stay in the ice chest for up to 6 hours, and still be far too hot to pull by hand.
Good luck, and have fun.