Yes, we are becoming a part-time employment country as a result of Obamacare, because employers have had to cut hours in order to comply with the requirements of Obamacare. Obamacare, just in the case of the Olive Garden, has resulted in workers not being allowed to work more than 28 hours, so that the company does not have to pay health care.
Employers that seized on obamacare as a chance to slash worker's hours and increase part-time jobs were bad employers to begin with. They clearly see their employees as numbers, not as human beings whose health needs are worth taking care of. The increase in part time work is a result of crony capitalism, not the healthcare mandate.