I agree with Rick, i.e. don't see it as a problem, although perhaps a somewhat unusual configuration, as Rick also believes.
Consider you have a non VLAN capable switch connected to a router, logically isn't it the same configuration?
Or, for the forgoing, replace the router with a L3 switch. On the L3 switch, although you now have the option of using an access port or trunk port with an SVI, wouldn't a "routed port" be the equivalent of the router?
As to a Etherchannel being used, logically it creates a single link, so I don't see where that matters. The real question is L2<>L3, and as above, it's the only way to do it with a non VLAN switch and a router, so it definitely can work just fine. Whether this is "best practice", when you have other options, I would say depends on other considerations.
BTW, sometimes I've used trunks to support L2 and L3 concurrently (such might, or might not, have also been using Etherchannel). In my experience, it often freaks out less experienced engineers as it's uncommon.
I've also used SVIs (usually with just 2 access ports for the VLAN), to support a p2p across a single link, i.e. only one access port has a physical cable connection. That too often confuses other engineers, at least initially, even when I explain its "why".
