The following year, he joined Polish side Legia Warsaw on a reserve contract, alongside compatriot Brian Iloski, and following technical director Ivan Kepčija, who had held the same role at Dinamo Zagreb.[4][5] He left the club in July 2019, having played for their reserve team in the III liga.[6]
Collegiate soccer
On his return to the United States, he enrolled at the Boston College, playing for the school soccer team, the Boston College Eagles.[2] In his first season with the Eagles, he made fifteen appearances, being nominated for the All-ACC Freshman Team.[3] The following season was curtailed by the COVID-19 pandemic in Boston, with Shapiro-Thompson having made six appearances, scoring once.[3] After another six appearances the following year, he suffered a torn ACL, but managed to recover to make sixteen appearances as a senior.[3] During his time at the college, he also played for Western Mass Pioneers in the USL League Two, though he only made one appearance, in the 2021 USL League Two Playoffs.