A non-401(k) Profit Sharing Plan allows rollovers from IRAs into the Plan. This Plan also allows for in-service distributions (using the 2 year/ 5 year rule.) Are the IRA rollover balances subject to the same distribution rules?

Yes if the plan document says so. Otherwise not.

Amounts rolled over to the plan can be withdrawn at any time, providing the rollover amounts are separately accounted for by the employer (a few exceptions apply). See Revenue Ruling 2004-12 available at http://www.irs.gov/pub/irs-drop/rr-04-12.pdf. … In this case, it appears the individual may withdraw the rollover amount at any time...

The plan document controls even if the law allows the plan to provide for IRA rollover amounts to be distributed in-service. The Revenue Ruling says the plan "may permit" withdrawals.