You can do that, but not for more than a couple days, before giving them light again. You don't want to see any signs of etiolation, or you will have to 'harden off' the plants back into light. If you have to hold them longer than that, try to find some better lighting, indirect sunlight or a bright fluorescent or LED bulb. Even if it's cold, the darkness will often promote etiolated growth, and that's not good.
I've actually had good results planting the tomatoes out in cold damp weather. I haven't ever had any cold damage whatsoever unless the temperature was below freezing overnight and the plant(s) were uncovered. I usually stick 'em out early, before the frost is over, and just toss old bed sheets/cardboard boxes weights down/similar protection overnight when frost is expected. So far, I've had great results, and good early results. Red (or black) plastic below the plants really helps. Just don't use fabric. The landscape fabric lets the soil underneath dry out, crust, grow weeds through, and be a mess.
You could put them out for a couple hours a day (assuming you have time) and then bring them back in, and herden them to the weather for a few days, and then move all your starts out early. You'll likely still need to cover them occasionally, with how cold this spring's been.
