If the government was issuing so much debt that it was crowding out corporate debt, then corporate debt would be a bargain. In other words, it's price would be low, meaning yields would be higher. Now consider this chart of the LQD -- the liquid bond fund:
The 5- year chart shows a rally, interrupted only by the sell-off at the beginning of the great recession. In fact,
In fact, when markets sold-off, the corporate bond market clearly caught a bid. Also note the increased volume on the rally. Additionally, we have a very bullish EMA picture.
There is no crowding out in the current market data.