No, a shill is someone who is paid to entice people to take a position that may be contrary to what the shill believe, so that the shill's master benefits.

Adam Back at Blockstream employs a large team of PR people to "correct misinformation" about large blocks. These people are shills because they are paid to promote a position that they may not believe in, a position that is hurtful for BTC (high fees / unreliable confirms), but one that benefits the employer Blockstream (by creating demand for their layer-2 solutions).