RSU's awarded in 2012 were converted upon vesting. He sold and realized a long term capital gain. Then he bought in the name of his qualified retirement plan.. He is 64 so there's no penalty for early withdrawal. The retirement plan is probably a roth IRA so the future gains will not be taxable. But excess contributions are subject to a 6% excise tax. Depending on his bracket the gain on the sale is taxed at up to 23.8% on a basis of zero. Assuming 3.60 average price the tax is is about 13K on the 54K gain. Now reinvest the 54K in the roth and pay 6% upfront on the 48k excess contribution (2880) but pay no taxes on any future capital gain.
You wouldn't do this if you thought the stock wasn't going to appreciate bigtime.