The liberals want to set drug prices in the US, the whole "allow people to buy drugs from foreign nations" is just the whip they're using to pressure the other lawmakers to allow them to set prices to avoid opening the US pharma market.
So the whip to pressure the conservatives is a free market, and the conservatives run from that idea.
Pharma is anything but a 'free market', it is one of the heaviest-regulated US industries. This would simply be allowing in competition that can easily undercut prices as the competition doesn't have the expenses incurred by US pharma companies to research, develop, and eventually, after up to decades, possibly bringing them to market. Many shady foreign companies copy US patented drugs that cost US pharma companies many millions at each step along the way and sell the knockoffs for a fraction.
This would put pressure on US pharma research, development, and sales to leave the US and cripple what remains.
If the goal is to globalize pharmaceuticals then US pharmaceutical regulations, laws, and procedures for testing and certification in the US will have to be lowered/reduced/softened to more closely match the global markets like Indonesia or they will cease to exist (in the US, at least).
I too want reasonable pharmaceutical costs and robust research and development of new drugs and treatments, etc. I just don't think loosing the foreign competition on US pharma that's effectively hamstrung by a cumbersome, inefficient, and achingly-slow regulatory structure seems wise.
I believe much more could be gained all around if serious reform, downsizing, modernization, and streamlining of the current US pharmaceutical regulatory structure could be accomplished. At that point opening US pharma markets to foreign competition would not matter as US companies could easily compete.
Competition is great. It drives innovation and keeps prices low. Having one competitor deliberately hamstrung is not competition or a 'free market'. In this case it amounts to targeted economic destruction of a nation's particular industry.