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If the tomatoes had never been warmed to room temperature after opening then I probably would at least consider freezing them. The big reason for not thawing and re-freezing most frozen vegetables is “loss of quality” of the “fresh-frozenness”. That is, flash-frozen vegetables that have been allowed to thaw and then re-freeze lose a lot of the qualities that we want in our frozen vegetables: a certain “fresh feel” when cooked. Since canned tomatoes never have that “fresh feel”, you don’t suffer the loss of quality. Who cares (or even notices) if a canned / frozen tomato feels a little soft?
But if they’ve been warmed to room temperature after opening (or, since the can / jar was likely already at room temperature when first opened, if they’ve been allowed to sit out for more than an hour or so after opening), then I’d toss them on principle, because of the potential for contamination while they were opened and left at room temperature. (Although tomatoes are less likely to have been fouled or contaminated in the first place because of their relatively high acid content.)
And if I have used them in cooking, then I don’t have a second thought about it: they can be frozen / refrozen indefinitely.