No, that's just a strategic move to keep the NDP down. Grits have been doing this with social democratic third parties for nearly a century, it ain't new. Most recently, Paul Martin campaigned with then CAW-chief Buzz Hargrove in 2004/6.
It's not just the union speech, it's Trudeau capitalizing "Labour" throughout his speech, as well as making Liberal party membership free and stating he wants to transform the party into a "movement".
It can only be a movement if it becomes the "Labour" party (ie: the Labour movement).
At least that's what has happened in Britain, Australia and New Zealand.
That has happened in exactly none of those places. In Australia and New Zealand the liberal party (that is to say, the pro-free trade party) merged with the conservative party (that is to say, the anti-free trade party), while in Britain the liberal party was reduced to third-party status.