He likely was, but chose Toronto. Odds are he wants to parlay a season here into a big contract next off-season.
Free agent players see 1/2 of Leafs entire Salary Cap tied up in just 4 forwards which also comprise 4 of their top 6, and see opportunity to play in Leafs top 6 alongside elite talent to prop up their stats and cash in big on their next contracts, by riding their coattails to their own financial success.
That is why Toronto despite being considered a Cup contender has open auditions for 2 X top 6 positions on LW and makes them so appealing from the outside looking in.
PTO and career minor leaguers, or players bought out, or not provided qualifying offers and all cut lose by previous teams are now lining up and applying for contracts and jobs with the Leafs riding shotgun beside Leafs core 4.
Gusev could literally start training camp on a PTO without an NHL contract, and yet start the year beside Matthews and Marner on Leafs top line, as long and he pops a few goals in the exhibition season and impresses a few people because the competition on the left side for the Leafs is wide open top to bottom on all lines entering training camp.