Not to be argumentative, but I don't think your advice is entirely accurate.
1. Cost of dtg has come down due to software. If you are printing on a white shirt, that cost will be around $0.25 for a full front. If black, it can vary, but with software, I've been able to take a design that would have cost $4.50 and got it down to $2.00 and the print still looked great. Just know the software and how to apply it to different designs to get the look you want. You can also run it through the RIP before printing for finding costs.
2. I've screen printed since 1998, I know how to screen print. I can tell you, this is more than just for people who don't know how to screen print. The profits and increased sales are greater than one can expect when worked right. Do a search and find out how much people's businesses have grown due to this technology.
3. Screen printing is not always more cost effective. Someone wants 12 shirts with a three color design, I can guarantee you, with time spent, supplies and ink is going to be more expensive than DTG, not simply pennies per shirt. You can sell these shirts at a higher price because of no screen charges and still make more in the end. It's not a matter of how much your ink costs are, it's a matter of knowing how to work your numbers to benefit you. The problem in this industry is people try to sell dtg shirts at screen printing prices. The quality of print on dtg can be so much greater than screen printing, we need to start pricing it accordingly.
As an FYI, it appears as if they already have a DTG, just adding screen printing to the mix.