No. It depends on their reasons. E.g. they may be indifferent because they think something is unrealistic and won’t get anywhere politically. When the situation changes, like something is imminent and gets national attention, then lots of formerly indifferent people think about it more and stop being indifferent: some become advocates and some become opponents. Since it’s possible most of them will turn out to be opponents, it’s not fair to say they think it’s good.
This happens not just with indifference but also with favor or opposition. When something becomes more important, relevant, urgent, etc., people think it over more and may switch sides. It may turn out their favor or opposition was superficial. Some people who appear to favor or oppose a policy will switch sides before the policy gets over the finish line of being implemented.
What people really value is complex and sometimes they don’t even know. What they do when something is immediately relevant and being decided tends to be a better indicator than what they said from a distance, but it’s a flawed indicator too. For example, people may say they support something because they think it’s a foregone conclusion, or they want to get along with their neighbors, or various other reasons, but if they thought stopping it was more realistic or more popular in their social circle then they’d oppose it, and their real preference, if they could choose their full situation, would be to oppose it.