You may need a PCV box reseal due to a leak, but that won't cause a squeak. Could be the belt tensioner. Tell them not to do the PCV until they know where the noise is coming from.

I don't know about the six cylinder, but the idler pulleys on the serpentine belts on the fives are notorious for losing bearings. A dying bearing squeaks, eh? Dealer told me that they have had cars lose the idler coming off the car carrier at delivery from the factory.
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01 V70 2.4 M5 and a Mini

I was just going to post a similar question. This is on a 99 V70T5. At 1100-1200 RPM, it makes a noise that is very hard to describe, it is metallic and sounds like a cross between a loose catalytic converter heat shield, and a pulley just barely rubbing against metal, with a touch of bearing noise thrown in.

Using a stethoscope, it cannot be heard anyplace other than the timing belt cover, which makes me suspect it is a failing bearing on the timing belt idler pulley or on the timing belt tensioner. It could possibly be the serpentine belt tensioner idler, which I can't safely reach with the stethoscope, but I do not hear the noise when listening to the alternator or power steering pump. (I'm not sure that means anything, since the noise would have to travel along a rubber belt to be heard at the PS pump or alternator). I am also curious about why it goes away above 1200 RPM, rather than getting worse.

The car only has 73,500 miles, and I had hoped to wait for the factory recommended 100,000 before doing the timing belt.

Is there anyone out there who can confirm or deny a relationship between timing belt roller bearings and a noise like this?

Wow! I didn't even think newer cars had a PCV, just a few vacuum lines going to the intake areas.
I would suggest you investigate the noise a little better and find out exactly where it is coming from. It might just be the cover of the Tbelt touching something.
Do not go back to the dealer until you know where the noise is coming from.

Klaus
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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)