Russia has given each and every excuse that you could possibly come up with in 2014 and again in 2022. If you're a defense industry consultant I'd expect you to be more than conversant with the run-up to the second episode of this war and not to swallow such things hook, line and sinker.

Note that nowhere in that article does it say that the Ukrainian side did that. For all we know this was a provocation, as Russia is won't to do. Alternative explanations have been present many times and none of them have stuck.

Also note that there was an endless build-up prior to the second phase of this invasion which had absolutely nothing to do with that particular incident even if it was done by the Ukrainian side, which I highly doubt given the fact that it was one of the pretexts used.

Finally: in that region there have been many actions by either side and no matter what: the Ukrainians are well within their right to kick out an invader, the myth of the separatists has been debunked solidly, until the little green men showed up there was no meaningful separatist activity.