It's sketchy as hell, and if big market clubs make a habit of coordinating FA signings with outside sponsors (and doing so so publicly), there'll be some pissed off small market owners and some clear language against this in the next CBA. Although the language is already pretty clear:
However, nothing in this Section 26.3(e) is intended to prohibit a Player
from entering into a sponsorship, endorsement or other commercial
arrangement with a local sponsor or entity with which his Club does
business but which is not a Club Affiliated Entity, in which the Player
receives something of value, provided the thing of value received is
commensurate with (i.e., not clearly in excess of) the fair market value of
the services rendered by the Player on behalf of the sponsor or entity.
With respect to any sponsorship or endorsement arrangement between a
Player and a national sponsor, any thing of value provided to a Player
under such arrangement shall be presumptively acceptable (i.e., such thing
of value need not meet the "fair market value" test set forth in the
preceding sentence), provided that such arrangement was not made at the
behest of the Player's Club or any other Club Actor. However, the NHL
shall have the right to challenge before the System Arbitrator, through an
expedited arbitration proceeding pursuant to the third sentence of Section
26.13(a) below, the bona fides of any such national sponsorship or
endorsement arrangement on the grounds that it was actually provided for
the benefit of a particular Club.