My first critique group got really bent with me when I refused to critique a manuscript in TNR 8 with 1/2" margins. The author worried about the cost of printing more pages.
I don't blame you--that's ridiculous!
If she's on a tight budget, she could just read the excerpt out to the group or ask for members to share copies, using different pen colors.
Crit copies don't have to be in standard MS format, either, but the font needs to be easy to read.
I print my crit copies like a magazine page with single spacing, double columns, and narrow margins--but a 12 font--printed on the clean side of used paper. OTOH, I've a bit more writing experience and have fewer corrections to make. My crit needs are for content and flow over technical typos.
When new members join we let them know that in the interest of saving paper they could print any way they wanted, so long as the font was readable. However, we made it clear to dress up the MS when it was formal submission time.
If they were a good group otherwise, it's okay to go back, but ask that members adapt to a larger font!
Point out that larger print makes it easier to spot things that need a fix!