Even for those that do think halting border crossings is bad, the consequences of making ICE change to a different IT solution is likely that ICE's bureaucracy is hampered and people detained at the border take longer to process and thus result in more hardship.

If the objective is to gain some immediate press exposure for immigrants rights issues, it seems totally rational, and it appears to have achieved the goal.

If the objective is to improve conditions for immigrants in ICE/CBP custody in the near term, it's not clear it will help, and it could definitely have unintended negative consequences. For example, ERO agents under increased pressure due to IT systems going down may be less likely to offer DA on humanitarian grounds, if it's just easier and less paperwork to deport en masse. Maybe there's a strong rational argument to be made in favor, but average citizens don't have complete information or authority to investigate, so it really seems to boil down to more of a "gut instinct" decision.

If the objective is improvement in conditions for immigrants in the longer term, it might be rational if it's part of a persistent, steady application of pressure to reform ICE/CBP/ORR through a combination of protests, opening cases to trigger judicial oversight, and lobbying to achieve change through legislative processes. But it's unclear if this kind of boycott is particularly effective use of time/resources towards that goal.