Most (if not all) politicians live on finding ways to take advantage of opportunities to advance their goals. Back when Trump started talking about restricting flights from China, the response from democrats was that he was promoting xenophobia, adding another weapon to his trade war with China, etc. People in the US mostly hadn’t noticed what was going on in China, yet.
When Amazon started having problems with “ships from China” items getting delayed, and pharmacies started having shortages (due to those also being impacted by delays from China), people gradually started noticing that something was not right in the world.
Then the House democrats had a closed door meeting, where Nadler tried to convince Pelosi to end the session and send everyone home (instead of having them stay in DC, where they were expected to mingle with each other and gather in groups to vote). Pelosi refused, likely because a) she would have been giving up, or postponing, some of her power, and b) she saw the possibility of opportunities to tack things onto legislation that “had to be passed”. Her recent efforts to push a 1400 page ‘coronavirus relief package’ that included things like carbon neutral requirements for airlines, diversity quotas, funding for ‘the arts’, etc, is evidence of her motives.
This issue would have been a problem, even if politics had not been involved. Politicians saw it as an opportunity, and some of the politics will end up making it an even bigger problem.